I don't think there is a Symphony of Science production that I have not enjoyed (I think it's the best use of auto-tuning I've ever heard), but this latest one seems particularly relevant to the subject matter of this blog.
I always love hearing Carl Sagan speak, and I am particularly happy about the inclusion of Oliver Sacks in this video (he wrote Musicophilia, which I highly recommend to everyone).
Wednesday, March 23, 2011
Tuesday, March 15, 2011
Music and the Brain: A Phenomenon
Whether you've thought about it or not, you've experienced the "cocktail party effect." The term may even sound familiar, as I've seen it crop up in popular media from time-to-time. Usually, the only significance applied to it is, "isn't this cool?" I shall elaborate.
The cocktail party effect is the phenomenon that in a crowded room of people with dozens of simultaneous conversations going on at once, our ear/brain duo is able to focus in on the one person that we really intend to listen to, and ignore extraneous conversational noise.
I was inspired to write this post when I was giving guitar-playing quizzes in a middle school. I allowed everyone in class to continue to practice on their guitars while I would walk to an individual and listen to their playing for a grade. Of course, with the confrontation of the teacher, students tend to become timid and play more quietly, while at the same time, the aggregate sound of 25+ other guitars being vigorously strummed is very loud. In accordance with the cocktail party effect, I was still able to discern exactly the sounds coming from the guitar that the quizzed student was playing while ignoring the rest.
Let's consider some variables (some of which I discussed in Music and the Brain: A Primer, of course) and how they relate to this effect.
Amplitude (volume): For a waveform, amplitude is the term that describes how far away from a central axis the waveform goes. In terms of sound, which is really a sequence of changes in air pressure, this means the difference between a high amount of pressure impacting one's eardrum and a low amount of pressure.
If we reduce the complexity of this effect to a situation with one listener and two speakers, we can explore the importance of amplitude. If you were listening to two people talking to you and one person whispered while the other shouted, who would be easier to hear? The louder person, of course, because the amplitude of their voice is so much greater that it overwhelms the effect of the tiny little changes in air pressure made by the other's whisper. I would hope that everyone over the age of 4 could follow that logic easily. Consider then, that in a crowded room, the average volume at which people are speaking is about the same. Sound does dissipate over distance, so you could potentially have the benefit of proximity; the person you want to listen to is closer, and thus louder to your ears. Yet sometimes you may be listening to someone further from you than another speaker. Our brains can still focus in on that person. Cool. Though without the benefit of greater amplitude, it makes things harder.
Frequency (pitch): For a waveform, frequency is the term that describes how close together the peaks of a wave are. The closer each wave is to the next, the higher the frequency, and the higher the pitch, of the sound. The beloved cochlea is able to distinguish between pitches (and we tend to favor higher pitches) by responding to the frequency of pressure oscillations.
In another situation, let us imagine you and a friend are inside a building when one of those really annoying, piercing, and loud fire alarms goes off. If you head toward the front door and your friend says to you, "wait, the fire exit is this way," you would likely be able to hear them. This is because the high-frequency hair cells in your cochlea would be reacting to the high frequencies at high amplitude (the alarm), but the middle-frequency hair cells would be reacting to the frequencies of your friends voice, even though their amplitude is lower. This effect is much more dramatic if a very loud but low-pitched sound is in the background and you need to listen to someone who speaks at a much higher frequency than that sound because of our brain's tendency to respond more dramatically to higher pitches (this also explains why whistling is so audible in most places).
Timbre (tone color): I previously defined this as a musical element, but it is most accurately a characteristic of sound. Importantly, however, it is not a property of waves as frequency and pitch are. Timbre is the "color" of a sound — it is not only the characteristic that enables us to distinguish a trumpet from a clarinet, it is also that which enables us to distinguish a father's voice from a brother's. As it happens, most sounds from most sources do not produce only one frequency. That's right, no matter how hard you try to sing perfectly on pitch, your voice will be producing additional frequencies. These additional frequencies are [essentially] higher versions of the fundamental pitch.
Consideration of this characteristic almost sounds like the nail-in-the-coffin for why we can hear one person over so many others at a cocktail party. People sound different, so if you are listening for a particular timbre, you'll be able to disregard others as meaningless noise. That, however, is not the end of this analysis. Recall my guitar-quizzing story. The differences in timbre from one guitar to another are extremely small. If I had to rely only on timbre to distinguish who I was listening to, I wouldn't have a chance.
Direction: We have two ears! How cool is that?!?! OK, don't get too excited. We also have two eyes, and their separation enables our brains to combine two two-dimensional images to determine depth and therefore form one three-dimensional perspective. Our ears do the same thing for sound. The auditory "picture" from each ear is compared to the other to determine from where a sound originated. However, there is a pretty significant difference between the eyes and ears where this analogy breaks down. The brain has to measure the time between the reception of a sound in one ear and the subsequent reception of that sound in the other, whereas that sort of direct measurement of timing isn't used to combine our eyes' visual images (at least not in the way that I understand it). The speed of sound is about 1100 feet/second. The distance between my ears is about 6.5 inches (yes, I just measured). That means it takes sound about half of a millisecond to get from one ear to another, and that's the best case scenario! The closer a sound gets to being straight in front of or behind a person, the more precise this measurement has to be in order to distinguish which ear the source is closer to.
So in the cocktail situation, we can focus our listening to a certain direction. Sure, it's easy to say that the person speaking to you is also the person you intend to listen to, and that that person is standing directly in front of you. However, you could prefer to listen to the gossip going on behind you and a bit to your left, and ignore the person in front of you while smiling and nodding anyway. In this situation, your brain has to identify the ideal ear-to-ear difference in sound and focus only on frequency/amplitude pairings that match the needed timing difference! This is even more incredible when one considers the "mixing" of sounds when they reach the ear. We only have one ear drum per ear, so it's not like we can devote ear drum A to speaker A, B to B, and C to C. All of the various frequencies, amplitudes, and timbres get mixed together in the air and when they reach our ear drums. This means that in order to focus on the sound of one person's voice, the brain must separate that mixed-together signal into at least one proper combination of frequency, amplitude, timbre, and direction.
Therefore, in order for me to properly listen to one guitar out of 30, my brain has some serious work to do. The amplitude of the guitar I want to hear isn't worth much; I have to rely on proximity to benefit from this variable at all. The timbre is almost worthless; the biggest factor on that seems to be how clearly the student creates sounds. Direction is vital, because there could easily be other guitars equally close to me, but the location of one matters most. Frequency in this situation is significantly beneficial; I am listening for a melody or chord progression that I know well, so my expectation of certain frequencies enables me to block out those that don't match.
I was going to follow the above analysis with an examination of current research, but I've already met the intended limit of length for this post. All of the above is rudimentary in the study of the cocktail party effect, and there is a lot of research still to do — research that has beneficial impacts on subjects ranging from cognitive psychology to sound engineering.
The questions that scientists are left asking center around how we are able to focus on these characteristics, which specifically addresses auditory masking (and cognitive sequencing to a lesser degree). If you are interested in knowing more, I recommend a review of such studies that was published in 2000: The Cocktail Party Phenomenon: A Review of Research on Speech Intelligibility in Multiple-Talker Conditions. (To be completely honest, I haven't read it yet, I just really want to publish this post and it looks like good research.)
The cocktail party effect is the phenomenon that in a crowded room of people with dozens of simultaneous conversations going on at once, our ear/brain duo is able to focus in on the one person that we really intend to listen to, and ignore extraneous conversational noise.
I was inspired to write this post when I was giving guitar-playing quizzes in a middle school. I allowed everyone in class to continue to practice on their guitars while I would walk to an individual and listen to their playing for a grade. Of course, with the confrontation of the teacher, students tend to become timid and play more quietly, while at the same time, the aggregate sound of 25+ other guitars being vigorously strummed is very loud. In accordance with the cocktail party effect, I was still able to discern exactly the sounds coming from the guitar that the quizzed student was playing while ignoring the rest.
Let's consider some variables (some of which I discussed in Music and the Brain: A Primer, of course) and how they relate to this effect.
 |
| I hope they don't mind me borrowing this image. |
If we reduce the complexity of this effect to a situation with one listener and two speakers, we can explore the importance of amplitude. If you were listening to two people talking to you and one person whispered while the other shouted, who would be easier to hear? The louder person, of course, because the amplitude of their voice is so much greater that it overwhelms the effect of the tiny little changes in air pressure made by the other's whisper. I would hope that everyone over the age of 4 could follow that logic easily. Consider then, that in a crowded room, the average volume at which people are speaking is about the same. Sound does dissipate over distance, so you could potentially have the benefit of proximity; the person you want to listen to is closer, and thus louder to your ears. Yet sometimes you may be listening to someone further from you than another speaker. Our brains can still focus in on that person. Cool. Though without the benefit of greater amplitude, it makes things harder.
 |
| Image from USRA. |
In another situation, let us imagine you and a friend are inside a building when one of those really annoying, piercing, and loud fire alarms goes off. If you head toward the front door and your friend says to you, "wait, the fire exit is this way," you would likely be able to hear them. This is because the high-frequency hair cells in your cochlea would be reacting to the high frequencies at high amplitude (the alarm), but the middle-frequency hair cells would be reacting to the frequencies of your friends voice, even though their amplitude is lower. This effect is much more dramatic if a very loud but low-pitched sound is in the background and you need to listen to someone who speaks at a much higher frequency than that sound because of our brain's tendency to respond more dramatically to higher pitches (this also explains why whistling is so audible in most places).
Timbre (tone color): I previously defined this as a musical element, but it is most accurately a characteristic of sound. Importantly, however, it is not a property of waves as frequency and pitch are. Timbre is the "color" of a sound — it is not only the characteristic that enables us to distinguish a trumpet from a clarinet, it is also that which enables us to distinguish a father's voice from a brother's. As it happens, most sounds from most sources do not produce only one frequency. That's right, no matter how hard you try to sing perfectly on pitch, your voice will be producing additional frequencies. These additional frequencies are [essentially] higher versions of the fundamental pitch.
 |
| Because of additional frequencies, the waveform of a voice looks more like this than it does the examples above. From UBC. |
Consideration of this characteristic almost sounds like the nail-in-the-coffin for why we can hear one person over so many others at a cocktail party. People sound different, so if you are listening for a particular timbre, you'll be able to disregard others as meaningless noise. That, however, is not the end of this analysis. Recall my guitar-quizzing story. The differences in timbre from one guitar to another are extremely small. If I had to rely only on timbre to distinguish who I was listening to, I wouldn't have a chance.
Direction: We have two ears! How cool is that?!?! OK, don't get too excited. We also have two eyes, and their separation enables our brains to combine two two-dimensional images to determine depth and therefore form one three-dimensional perspective. Our ears do the same thing for sound. The auditory "picture" from each ear is compared to the other to determine from where a sound originated. However, there is a pretty significant difference between the eyes and ears where this analogy breaks down. The brain has to measure the time between the reception of a sound in one ear and the subsequent reception of that sound in the other, whereas that sort of direct measurement of timing isn't used to combine our eyes' visual images (at least not in the way that I understand it). The speed of sound is about 1100 feet/second. The distance between my ears is about 6.5 inches (yes, I just measured). That means it takes sound about half of a millisecond to get from one ear to another, and that's the best case scenario! The closer a sound gets to being straight in front of or behind a person, the more precise this measurement has to be in order to distinguish which ear the source is closer to.
So in the cocktail situation, we can focus our listening to a certain direction. Sure, it's easy to say that the person speaking to you is also the person you intend to listen to, and that that person is standing directly in front of you. However, you could prefer to listen to the gossip going on behind you and a bit to your left, and ignore the person in front of you while smiling and nodding anyway. In this situation, your brain has to identify the ideal ear-to-ear difference in sound and focus only on frequency/amplitude pairings that match the needed timing difference! This is even more incredible when one considers the "mixing" of sounds when they reach the ear. We only have one ear drum per ear, so it's not like we can devote ear drum A to speaker A, B to B, and C to C. All of the various frequencies, amplitudes, and timbres get mixed together in the air and when they reach our ear drums. This means that in order to focus on the sound of one person's voice, the brain must separate that mixed-together signal into at least one proper combination of frequency, amplitude, timbre, and direction.
 |
| Surround Sound diagrams represent this idea well. Image from Wikipedia. |
Therefore, in order for me to properly listen to one guitar out of 30, my brain has some serious work to do. The amplitude of the guitar I want to hear isn't worth much; I have to rely on proximity to benefit from this variable at all. The timbre is almost worthless; the biggest factor on that seems to be how clearly the student creates sounds. Direction is vital, because there could easily be other guitars equally close to me, but the location of one matters most. Frequency in this situation is significantly beneficial; I am listening for a melody or chord progression that I know well, so my expectation of certain frequencies enables me to block out those that don't match.
I was going to follow the above analysis with an examination of current research, but I've already met the intended limit of length for this post. All of the above is rudimentary in the study of the cocktail party effect, and there is a lot of research still to do — research that has beneficial impacts on subjects ranging from cognitive psychology to sound engineering.
The questions that scientists are left asking center around how we are able to focus on these characteristics, which specifically addresses auditory masking (and cognitive sequencing to a lesser degree). If you are interested in knowing more, I recommend a review of such studies that was published in 2000: The Cocktail Party Phenomenon: A Review of Research on Speech Intelligibility in Multiple-Talker Conditions. (To be completely honest, I haven't read it yet, I just really want to publish this post and it looks like good research.)
Saturday, March 5, 2011
Miscommunication
Yesterday was completely bizarre. There's a nearby school district that is rumored to have a full-time HS music opening soon, as one of their music teachers is going to retire (an instrumental job, it turns out, but I'll apply). I was scheduled to work a half day as a sub Friday morning at this district — my first time there. I wanted to make a good impression.
First of all, everyone's noticed this but I still must complain: Why must schools have eight doors at their main entrance and only unlock ONE of them? Most of the time, they won't even indicate which magical door is the one people are supposed to use! I'm sure the secretaries have a great time watching, on their security cameras, people like me try every damn door before finding the correct one. This happens to me every morning, because I work at so many different schools I never remember which door is the special one. I resent this.
I knew that I was going to be a sub for a MS learning support teacher, and I was glad I could do so in half a day just in case I turn out to not be good at working with these groups of students. Before my first class started, I got a call from the office asking if I would work at the HS in the afternoon, which I accepted. These morning classes went rather well. I was even warned about one boy who particularly hates male substitutes who turned out to be absolutely no trouble at all.
I returned to the office at about 11:00 to get my HS assignment and they said that they thought I would be needed at 12, so I was able to go pick up lunch at a nearby deli. I got a wrap to go and drove to the HS where I couldn't find a good place to park. I drove around different lots, clueless, until I found a spot. I sat in my car and continued to listen to a symphony on the radio and ate my lunch. When I was almost done, an administrator (the principal, I think) walked up next to my door. They had been made nervous about me due to my driving around and subsequent sitting in my car, so the first impression they had of me was as a clueless, embarrassed sub.
I finished my last bite and went to the office where I found out that I wasn't needed until 1:00. I went to the faculty room to read and met a couple other teachers. I liked the environment there. Most faculty rooms are busy with a gaggle of women talking about American Idol, but this room had a diversity of gender, ages, and conversation topics. I'd like to work with these people. I met a teacher's aide, Mr. G, who told me he works with the teacher I would be subbing for, as well as what I would be teaching: ESL. Multiple people told me at that point, "Uh oh, do you speak Spanish? You'll be working with a boy who doesn't speak any English." I barely speak basic Spanish.
About 10 minutes before class I went to the room I was to teach in and looked for lesson plans — nada. Then the boy who speaks no English, whose name I'll change to Frank, arrived. He was the only student, so I would have no one else to translate even basic things. I greeted him and asked if he had any work he could do or a book to read, and couldn't get my questions across at all. On Thursday, too, I didn't have lesson plans, and on that day I called their office and they were helpful. On this Friday I called the office and essentially got laughed at. The conversation ended thusly: "OK, I guess...just let me know if anything arrives there"..."*chuckle* Yeah, sure." I turned around and looked at Frank. He returned my gaze blankly. I somehow got him to show me his agenda which I used to find out how long he was supposed to be with me (another hour and some), then I got a piece of paper and pens and said "let's play a game." Just then, Mr. G arrived. It turns out he was e-mailed the plans, which he then gave to me. The plans were rather limited; they said nothing about Frank's level, abilities, or faculties, and barely told me what to do. Mr. G, fortunately, knew where a folder that they work from was stored and retrieved it for us. Frank was on page 2 of the first ESL picture dictionary. He had a worksheet to do, so I taught him new words.
His accent was incredibly heavy and he spoke with the timidity of a frightened child. I worked with him on making 's' sounds in words with an 's'. I had to teach him the difference between 'm' and 'n', even though Spanish uses both. I had to teach him the difference between "in" and "on," which is not an easy task. Ultimately, we got through the class, and I do think he had a good grasp of almost 10 new words as well as some new sentence structures. The lesson plans ended here, but it was only 2:15. I asked Mr. G (who had been working with someone else this whole time) if this teacher has any other students arriving. "I think she usually goes to the middle school at this time," he told me. Great. Again, it's a good thing he knew this and I met him. I went to the office, which called the MS office and confirmed that I was needed there.
I drove to the MS and found out that there were two students I was supposed to work with, but nobody knew where. A secretary called some teachers to find out what was typically done and no one had any useful information. She eventually had to use the intercom to call these students to the office because she couldn't find them using phone calls. One came by and explained that he was doing something else with another teacher, so he was sent back to that. As long as these students had somewhere else to be, it would be pointless to just find a room for me to supervise them in. The secretary was now on a quest to find the second student, but I was no longer needed, and went home.
Well, almost. I had forgotten to return my substitute badge to the HS office, so I had to return there and embarrass myself again.
I hope that the next time I sub there I can redeem myself and the offices (particularly HS) can redeem themselves. Maybe then I'll be able to want to work there again.
First of all, everyone's noticed this but I still must complain: Why must schools have eight doors at their main entrance and only unlock ONE of them? Most of the time, they won't even indicate which magical door is the one people are supposed to use! I'm sure the secretaries have a great time watching, on their security cameras, people like me try every damn door before finding the correct one. This happens to me every morning, because I work at so many different schools I never remember which door is the special one. I resent this.
I knew that I was going to be a sub for a MS learning support teacher, and I was glad I could do so in half a day just in case I turn out to not be good at working with these groups of students. Before my first class started, I got a call from the office asking if I would work at the HS in the afternoon, which I accepted. These morning classes went rather well. I was even warned about one boy who particularly hates male substitutes who turned out to be absolutely no trouble at all.
I returned to the office at about 11:00 to get my HS assignment and they said that they thought I would be needed at 12, so I was able to go pick up lunch at a nearby deli. I got a wrap to go and drove to the HS where I couldn't find a good place to park. I drove around different lots, clueless, until I found a spot. I sat in my car and continued to listen to a symphony on the radio and ate my lunch. When I was almost done, an administrator (the principal, I think) walked up next to my door. They had been made nervous about me due to my driving around and subsequent sitting in my car, so the first impression they had of me was as a clueless, embarrassed sub.
I finished my last bite and went to the office where I found out that I wasn't needed until 1:00. I went to the faculty room to read and met a couple other teachers. I liked the environment there. Most faculty rooms are busy with a gaggle of women talking about American Idol, but this room had a diversity of gender, ages, and conversation topics. I'd like to work with these people. I met a teacher's aide, Mr. G, who told me he works with the teacher I would be subbing for, as well as what I would be teaching: ESL. Multiple people told me at that point, "Uh oh, do you speak Spanish? You'll be working with a boy who doesn't speak any English." I barely speak basic Spanish.
About 10 minutes before class I went to the room I was to teach in and looked for lesson plans — nada. Then the boy who speaks no English, whose name I'll change to Frank, arrived. He was the only student, so I would have no one else to translate even basic things. I greeted him and asked if he had any work he could do or a book to read, and couldn't get my questions across at all. On Thursday, too, I didn't have lesson plans, and on that day I called their office and they were helpful. On this Friday I called the office and essentially got laughed at. The conversation ended thusly: "OK, I guess...just let me know if anything arrives there"..."*chuckle* Yeah, sure." I turned around and looked at Frank. He returned my gaze blankly. I somehow got him to show me his agenda which I used to find out how long he was supposed to be with me (another hour and some), then I got a piece of paper and pens and said "let's play a game." Just then, Mr. G arrived. It turns out he was e-mailed the plans, which he then gave to me. The plans were rather limited; they said nothing about Frank's level, abilities, or faculties, and barely told me what to do. Mr. G, fortunately, knew where a folder that they work from was stored and retrieved it for us. Frank was on page 2 of the first ESL picture dictionary. He had a worksheet to do, so I taught him new words.
His accent was incredibly heavy and he spoke with the timidity of a frightened child. I worked with him on making 's' sounds in words with an 's'. I had to teach him the difference between 'm' and 'n', even though Spanish uses both. I had to teach him the difference between "in" and "on," which is not an easy task. Ultimately, we got through the class, and I do think he had a good grasp of almost 10 new words as well as some new sentence structures. The lesson plans ended here, but it was only 2:15. I asked Mr. G (who had been working with someone else this whole time) if this teacher has any other students arriving. "I think she usually goes to the middle school at this time," he told me. Great. Again, it's a good thing he knew this and I met him. I went to the office, which called the MS office and confirmed that I was needed there.
I drove to the MS and found out that there were two students I was supposed to work with, but nobody knew where. A secretary called some teachers to find out what was typically done and no one had any useful information. She eventually had to use the intercom to call these students to the office because she couldn't find them using phone calls. One came by and explained that he was doing something else with another teacher, so he was sent back to that. As long as these students had somewhere else to be, it would be pointless to just find a room for me to supervise them in. The secretary was now on a quest to find the second student, but I was no longer needed, and went home.
Well, almost. I had forgotten to return my substitute badge to the HS office, so I had to return there and embarrass myself again.
I hope that the next time I sub there I can redeem myself and the offices (particularly HS) can redeem themselves. Maybe then I'll be able to want to work there again.
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