Amplifying sound is the act of making a sound louder to the human ear. It relies on the process of increasing the amplitude of the sound wave, which is where "amplification" comes from. As I mentioned in a much earlier post, our perception of loudness corresponds to the amplitude of sound waves. Therefore, to make a sound seem louder, you need to find a way to increase the amplitude of its waveform. This can be done in a couple of ways.
The simplest way to amplify the volume of sound is when it is produced by an acoustic instrument. Striking a guitar string harder, blowing more air or with more force into a wind instrument, and beating a drum with more force are all ways to amplify the sound produced by acoustic instruments. As you can recall, the defining characteristics that determine the pitch of the sound produced are the length and thickness of the guitar string, or length and width of the air cavity in a wind instrument. Because this does not change during these processes, the pitch is able to remain constant while the sound is amplified.
The more interesting form of sound amplification, in my opinion, is the electronic/digital amplification that exists universally in our technology today. A great example of how this works relies on a slightly older piece of technology, a record player with electronic amplification. A vinyl record reproduces sound as the needle of the record player spins through its grooves and vibrates. The record player is able to convert these small vibrations into electrical signal. In the amplifier, this current is strengthened and reproduced as sound at a much louder volume. Much of our other technology works in the same way - electrical impulses are increased in strength in order to produce a louder sound. This is how microphones work as well as musical instrument amplifiers, such as guitar amps.
The existence of sound amplification brings up a few more questions about when it is necessary and the ways in which sound travels. Obviously in a small, quiet room, a guitar amp is not needed to hear the sound produced by a guitarist. What happens if it is a long room, however, and the guitar player is very far away? Though it may seem quiet, it may not be as easy for you to hear the guitar player without amplification if you are situated at opposite ends of the room. This pertains to the inverse square law, which relates the amplitude of sound to the distance it travels from its source to a listener. The law states that as the distance doubles, the intensity of the sound is decreased by a factor of four. This corresponds to a constant drop of six decibels each time the distance is doubled. Because of this, in certain cases sound amplification may be necessary simply due to the distance that sound needs to travel. This is especially relevant in large concert halls or outdoor venues.
Works Cited:
Friday, January 22, 2016
Wednesday, January 13, 2016
Haas Effect / Precedence Effect
The Haas effect and the precedence effect are effectively two names for the same psychoacoustic phenomenon and can be used interchangeably for the most part. Haas refers to Helmut Haas, the scientist credited with first describing this effect, while precedence provides a better sense as to what the effect actually is. I did explore some psychoacoustic phenomena during my first semester studies, but decided to put off study of the precedence effect until now due to its relevance. The precedence effect is a fundamental reason that we are able to perceive sound dimensionally, which relates directly to my previous post about stereo imaging.
The precedence effect occurs when we hear an initial sound and then its reflections (echos/delays, reverberations) approximately 1-40 milliseconds later. The information that arrives in our ears during this short period is critical in how our brains determine the location or width of a sound. This is the precedence effect in a nutshell; in reality it is a very simple phenomenon to understand if you do not dive deeply into neuroscience, and within that area there is still much to discover. A basic understanding of this effect can still be very useful for a musician or producer.
The precedence effect, along with stereo imaging, is often used in the mixing process in music production in order to make an instrument sound "wider" or fit better into the mix. By using a delay/echo audio plugin on a single channel, you can add a delay that falls into the Hass range, 1-40 ms. You can adjust this value to help your instrument or sound fall into the ideal place in the mix. It is important to consider the other parameters in the delay plugin and make sure that it is subtle enough to take advantage of the precedence effect without adding unnecessary echo. It is also possible to use the precedence effect to make a mono recording sound like a full stereo recording. This process is described succinctly here.
The precedence effect, along with stereo imaging, is often used in the mixing process in music production in order to make an instrument sound "wider" or fit better into the mix. By using a delay/echo audio plugin on a single channel, you can add a delay that falls into the Hass range, 1-40 ms. You can adjust this value to help your instrument or sound fall into the ideal place in the mix. It is important to consider the other parameters in the delay plugin and make sure that it is subtle enough to take advantage of the precedence effect without adding unnecessary echo. It is also possible to use the precedence effect to make a mono recording sound like a full stereo recording. This process is described succinctly here.
Works Cited:
Monday, January 11, 2016
Stereo Imaging
Stereo imaging presents another interesting connection between light and sound. The way we perceive depth relies on the fact that we have two eyes that perceived slightly different images due to their spacing. When our brain puts these two flat images together, we are able to see depth. Our ears work in a very similar way in the perception of sound. By hearing slightly different sounds in each ear, our brain is able to corroborate them to create a sense of spacial awareness. This should be second nature to you, as you certainly use your spacial sense of hearing on a daily basis.
The production of stereo music takes advantage of the sense of depth that our ears are able to produce. A song in stereo means that the two speakers or two headphones/earbuds actually play slightly different versions of the same song. Stereo imaging is the process of using the stereo reproduction of sound to create music that has audible depth and width. A song with good stereo imaging tends to sound more natural and allows instruments to have more clarity in the mix. If you close your eyes while listening to a well-produced recording of a jazz trio, you should be able to easily envision the location of each musician in front of you due to the recording's stereo imaging.
Achieving a recording with good stereo imaging is not an easy process. When recording acoustic instruments, stereo recording techniques need to be utilized in order to capture audio for both sound channels while also utilizing specific types of microphones that properly capture the depth and width of specific instruments.
In post production, after a performance has already been recorded, digital audio plugins that simulate the effect of stereo imaging can be carefully used to make a recording sound more natural or full. Stereo imaging can also be used to make a more well-mixed song by allowing each instrument to have its own physical space. This process can be especially important in the creation of electronic music, which will almost never be recorded by using a microphone. To achieve a good stereo image in the context of electronic music will effectively always require the use of stereo imaging plugins. In the mastering stages of producing a song, stereo imaging can be applied to different frequency ranges instead of specific instruments. In this case, higher frequencies are often manipulated to sound more wide, while lower frequencies are kept in the middle. This can allow a mix to sound more clear by granting new space to the different frequency ranges of a song.
Works Cited:
"Introduction to Stereo Imaging -- Theory." Cardiff School of Computer Science and Informatics. Web. 11 Jan. 2016.
"Stereo Imaging." CDT Audio. Web. 11 Jan. 2016.
The production of stereo music takes advantage of the sense of depth that our ears are able to produce. A song in stereo means that the two speakers or two headphones/earbuds actually play slightly different versions of the same song. Stereo imaging is the process of using the stereo reproduction of sound to create music that has audible depth and width. A song with good stereo imaging tends to sound more natural and allows instruments to have more clarity in the mix. If you close your eyes while listening to a well-produced recording of a jazz trio, you should be able to easily envision the location of each musician in front of you due to the recording's stereo imaging.
Achieving a recording with good stereo imaging is not an easy process. When recording acoustic instruments, stereo recording techniques need to be utilized in order to capture audio for both sound channels while also utilizing specific types of microphones that properly capture the depth and width of specific instruments.
In post production, after a performance has already been recorded, digital audio plugins that simulate the effect of stereo imaging can be carefully used to make a recording sound more natural or full. Stereo imaging can also be used to make a more well-mixed song by allowing each instrument to have its own physical space. This process can be especially important in the creation of electronic music, which will almost never be recorded by using a microphone. To achieve a good stereo image in the context of electronic music will effectively always require the use of stereo imaging plugins. In the mastering stages of producing a song, stereo imaging can be applied to different frequency ranges instead of specific instruments. In this case, higher frequencies are often manipulated to sound more wide, while lower frequencies are kept in the middle. This can allow a mix to sound more clear by granting new space to the different frequency ranges of a song.
Works Cited:
"Introduction to Stereo Imaging -- Theory." Cardiff School of Computer Science and Informatics. Web. 11 Jan. 2016.
"Stereo Imaging." CDT Audio. Web. 11 Jan. 2016.
The Doppler Effect
The Doppler effect one of the most interesting phenomena related to sound. In order for the Doppler effect to be observed, something must be producing a constant sound while moving relative to an observer. The result of this is something that many people have experienced or can easily perceive. You may have noticed when an ambulance passes by you on the road that its siren seems to change pitch. Interestingly, the pitch of the siren will seem constant to the person driving the vehicle. The pitch variation that you perceive is a result of the Doppler effect.
What causes the changing pitch of this sound is the movement of its source. The siren produces a sound of a constant frequency, but its distance relative to you changes, which effectively changes the wavelength of the sound wave that is generated. Because the speed of sound is constant and proportional to wavelength * frequency, the changing wavelength causes the frequency to change. This is the root cause of the Doppler effect. The way we perceive the pitch of sound is related to the frequency, so this explains how we can hear the Doppler effect as it applies to sound waves. The Doppler effect is also present in light waves, a characteristic that is critical in the study of astronomy. As my blog focuses on sound, I will not go into depth about this aspect of the Doppler effect, but the this source provides good introductory information if you are interested.
As I begin my second semester, the focus of my studies is shifting toward the recording and reproduction of sound, as well as the digital processing of sound. The Doppler effect exists in the reproduction of sound in certain amps and speakers. Leslie cabinets, commonly used amplifiers for Hammond organs, rely on rotational motion in the production of sound. This gives them a unique and often desirable quality for some musicians. Soon, I will analyze the changing frequencies of sound produced by a Leslie cabinet as an example of the Doppler effect.
Works Cited:
"The Doppler Effect." The Doppler Effect. Physics Classroom. Web. 11 Jan. 2016.
"Doppler Effect." Hyper Physics. Web. 11 Jan. 2016.
What causes the changing pitch of this sound is the movement of its source. The siren produces a sound of a constant frequency, but its distance relative to you changes, which effectively changes the wavelength of the sound wave that is generated. Because the speed of sound is constant and proportional to wavelength * frequency, the changing wavelength causes the frequency to change. This is the root cause of the Doppler effect. The way we perceive the pitch of sound is related to the frequency, so this explains how we can hear the Doppler effect as it applies to sound waves. The Doppler effect is also present in light waves, a characteristic that is critical in the study of astronomy. As my blog focuses on sound, I will not go into depth about this aspect of the Doppler effect, but the this source provides good introductory information if you are interested.
As I begin my second semester, the focus of my studies is shifting toward the recording and reproduction of sound, as well as the digital processing of sound. The Doppler effect exists in the reproduction of sound in certain amps and speakers. Leslie cabinets, commonly used amplifiers for Hammond organs, rely on rotational motion in the production of sound. This gives them a unique and often desirable quality for some musicians. Soon, I will analyze the changing frequencies of sound produced by a Leslie cabinet as an example of the Doppler effect.
Works Cited:
"The Doppler Effect." The Doppler Effect. Physics Classroom. Web. 11 Jan. 2016.
"Doppler Effect." Hyper Physics. Web. 11 Jan. 2016.
Saturday, December 19, 2015
Equal Tempered Tuning & Flaws in Just Tuning
Just tuning presents an interesting method of tuning the different notes of a scale based on specific frequency ratios, and ultimately ends up with twelve notes of unique frequency intervals that are perfectly harmonic. While this sounds like the best possible tuning system in theory, it runs into some substantial problems in practice. For example, when an instrument is tuned to C, the minor third of D-F ends up having a different frequency ratio than the normal minor third, C-Eb. There are many other cases in which these harmonic inconsistencies occur, such as changing the key of the song, and this leads to dissonance and a lack of flexibility in playing music.
Equal tempered tuning, also known as equal temperament tuning, aims to resolve the problems created by just tuning. It does so by making the twelve semitones of an octave equally spaced in terms of the relationship of their frequencies. This process adds consistency to the tuning process that just tuning lacks, but loses some of the harmonic purity of the fractional intervals. The relationship between the frequencies of notes in equal tempered tuning is given by the equation, frequency ratio = 2(n/12), where n is the number of semitones (The Physics of Music and Color). To hear a comparison between equal temperament and just tuning, check out this video.
The general consensus is that the flexibility given by equal temperament tuning is essential and makes up for the lack of purity that is achieved through just tuning.
Equal tempered tuning, also known as equal temperament tuning, aims to resolve the problems created by just tuning. It does so by making the twelve semitones of an octave equally spaced in terms of the relationship of their frequencies. This process adds consistency to the tuning process that just tuning lacks, but loses some of the harmonic purity of the fractional intervals. The relationship between the frequencies of notes in equal tempered tuning is given by the equation, frequency ratio = 2(n/12), where n is the number of semitones (The Physics of Music and Color). To hear a comparison between equal temperament and just tuning, check out this video.
The general consensus is that the flexibility given by equal temperament tuning is essential and makes up for the lack of purity that is achieved through just tuning.
Works Cited:
1. Gunther, Leon. The Physics of Music and Color. New York, New York: Springer, 2012.
Cents and Musical Intervals
While the western musical scale is broken into twelve notes, we often need more specific ways of describing the pitch of a sound, especially during the tuning process. For example, let's say that you are tuning one of your guitar's strings to the E note played by a piano. As you twist your tuning peg and strike the corresponding string, you get closer the frequency of the E and eventually reach the point where the frequency of your string is lower than F but higher than E. How can we quantify this difference? The piano player may tell you that you are 50 cents sharp of E, but what does this mean?
The chromatic scale is broken into twelve notes, but the cents system allows us to further break this up. The basic definition of this is that the interval between two semitones consists of 100 cents, evenly spaced frequency values between the two notes. Since an octave consists of twelve notes in a chromatic scale, we also know that an octave is made up of 1200 cents. Given this understanding, we now know when the pianist tells us that we are 50 cents sharp of E when tuning, our note is tuned exactly in between E and F. Though this frequency does not have a specific letter name, it can easily be quantified by using the cents system.
Many electronic tuning devices (or tuning apps) can help you tune your instrument to standard pitches. With remarkable precision, these devices are often able to show how many cents sharp or flat your detuned note is in order to help you reach the ideal frequency.
The chromatic scale is broken into twelve notes, but the cents system allows us to further break this up. The basic definition of this is that the interval between two semitones consists of 100 cents, evenly spaced frequency values between the two notes. Since an octave consists of twelve notes in a chromatic scale, we also know that an octave is made up of 1200 cents. Given this understanding, we now know when the pianist tells us that we are 50 cents sharp of E when tuning, our note is tuned exactly in between E and F. Though this frequency does not have a specific letter name, it can easily be quantified by using the cents system.
Many electronic tuning devices (or tuning apps) can help you tune your instrument to standard pitches. With remarkable precision, these devices are often able to show how many cents sharp or flat your detuned note is in order to help you reach the ideal frequency.
Works Cited:
1. Gunther, Leon. The Physics of Music and Color. New York, New York: Springer, 2012.
The Just Chromatic Scale
The western musical scale consists of twelve notes, each a semitone (half step) apart, and the scale consisting of all twelve notes is called the chromatic scale. Tuning an instrument to be able to play all twelve half steps of the chromatic scale adds a bit more difficulty to the process of tuning a pentatonic or diatonic scale.
Starting with the eight frequencies of a just diatonic scale, major third intervals are used to calculate the needed sharp/flat notes to complete the chromatic scale. Both descending and ascending major thirds can be used to find the ratios of the new notes, and the process of reducing the octave, as mentioned in my previous post, can be used to ultimately end up with the twelve ascending ratios of a chromatic scale. The following graphic is very useful in understanding the just chromatic tuning process:
Starting with the eight frequencies of a just diatonic scale, major third intervals are used to calculate the needed sharp/flat notes to complete the chromatic scale. Both descending and ascending major thirds can be used to find the ratios of the new notes, and the process of reducing the octave, as mentioned in my previous post, can be used to ultimately end up with the twelve ascending ratios of a chromatic scale. The following graphic is very useful in understanding the just chromatic tuning process:
(The Physics of Music and Color)
Works Cited:
1. Gunther, Leon. The Physics of Music and Color. New York, New York: Springer, 2012.
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