Week 1: Nature of Sound Flashcards

Question

What is the dynamic range of a microphone?

Answer 1

The decibels in which it will reproduce the sound properly.

Answer 2

noise floor and distortion - the noise floor or the quietest sound that can be produced clearly above the the hiss that the device is putting out - distortion when the sound is so loud it can't reproduce it and gives an ugly crackling or upper harmonics to the signal.

Answer 3

The range from its quietest to loudest section.

Answer 4

True This is the quietest thing that can be heard.

Answer 5

False. The maximum amplitude inside the computer is not 0 dBSPL. It is 0dBFS or 0 decibels Full Scale.

Answer 6

expanders, gates, compressors, and limiters

Answer 7

This term refers to a contour that represents a constant loudness for all audible frequencies. A contour having a sound pressure level (SPL) of 40dB at 1kHz is arbitrarily defined as a 40-phon contour. -Sweetwater

Answer 8

Fletcher and Munson were researchers in the ’30s who first accurately measured and published a set of curves showing the human ear’s sensitivity to loudness verses frequency. They conclusively demonstrated that human hearing is extremely dependent upon loudness. The curves show the ear to be most sensitive to sounds in the 3kHz to 4kHz area. This means sounds above and below 3–4kHz must be louder in order to be heard just as loud. For this reason, the Fletcher-Munson curves are referred to as “equal loudness contours.” They represent a family of curves from “just heard,” (0dB SPL) all the way to “harmfully loud” (130dB SPL), usually plotted in 10dB loudness increments. Though the Fletcher-Munson Curves are by far the most widely known contours, there have been others defined in recent years that some engineers think are more accurate - Sweetwater

Answer 9

A subjective unit of apparent loudness. A phon is defined as the sound pressure level of a pure sine wave tone that sounds equal in loudness to some other sound(s) in question. Because of the ear’s complicated response versus frequency characteristics (see Fletcher Munson Curves) you can’t accurately relate the perceived loudness of sounds directly to their sound pressure level as read on a sound level meter. The phon allows us to relate this perceived loudness of sound to objective measurements of that loudness. -Sweetwater

Answer 10

We perceive frequency as high and low pitch and we tend to use "frequency" and "pitch" interchangeably. Frequency is related to how fast sound is vibrating. A low frequency wave has slow pulses and a high frequency wave has fast pulses.

Answer 11

They are independent. You can have a high frequency, low amplitude wave/sound or a low frequency, high amplitude wave/sound. This is important because audio effects can be utilized that impact only certain parts of the sound.

Answer 12

Timbre is the collection of sound in multiple frequencies. This might also be referred to as the spectrum.

Answer 13

A single frequency sine wave. But that rarely happens. Every instrument has energy at multiple frequencies.

Answer 14

Harmonics, also called overtones or partials.

Answer 15

Raise the amplitude of the bottom frequency.

Answer 16

An equalizer is a collection of filters (e.g. a filter that changes the amplitude of different frequencies.).

Answer 17

Lowest - 20 Hz Highest - 20,000Hz=20kilohertz (young children can hear this but your high end dissipates naturally as you get older) Adults hear about 18,000Hz (18 kilohertz) at the upper end. with females hearing slightly higher.

Answer 18

1 vibration per second.

Answer 19

As we get to the higher or lower ends it gradually diminishes and there are variations in the middle. It's as if our ears act like an EQ and equipment has this kind of frequency response curve as well.

Answer 20

Frequency Response is the Frequency Range versus Amplitude. In other words, at 20 Hz, a certain input signal level may produce 100 dB of output. At 1 kHz, that same input level may produce 102 dB of output. At 10 kHz, 95 dB, and so on. A graph of all the frequencies plotted versus level is the Frequency Response Curve (FRC) of the monitor. When you see a Frequency Response specification for a monitor, the manufacturer is telling you that for a given input signal, the listed range of frequencies will produce output within a certain range of levels. For example: 20 Hz to 20 kHz +/- 3 dB. For these frequencies, the monitor will output signals that are within a 6 dB (+/- 3 dB) range. This does not mean that the speaker won’t reproduce frequencies outside this range, it will! But frequencies outside the range will be more than 3 dB off from the reference level. - sweetwater

Answer 21

The way we perceive sound. A field of science that studies how we perceive sound and extract useful information from acoustical signals. It concerns itself primarily with low-level functions of the auditory system and thus doesn’t much overlap with the study of music or aesthetics. Basic psychoacoustical research is mainly directed toward such topics as directional hearing, pitch, timbre and loudness perception, auditory scene analysis (the separation of sound sources and acoustical influences from sound signals) and related lower functions, such as the workings of our ears, neural coding of auditory signals, the mechanisms of interaction between multiple simultaneously heard sound sources, neural pathways from ears to the auditory cortex, their development and the role of evolution in the development of hearing. Psychoacoustical research has resulted in an enormous amount of data which can readily be applied to sound compression, representation, production and processing, musicology, speech recognition and composition, to give just a few examples. - sweetwater

Answer 22

When any sounds that contain similar frequencies are played simultaneously, the weaker sound tends to have those overlapping frequencies covered – ‘masked’ – by the frequencies from the stronger sound (especially in a dense mix). The frequencies of the weaker sound are still there; they are just not discernable over the more dominant sound with the same frequencies. Masking is a fact of life in audio, and not entirely a bad thing, either. Often when sounds are masked you tend to not miss them. An example of practical applications where masking plays a big part are audio CODECs, which often identify and eliminate masked sounds from an audio file in order to make the overall file size smaller. -sweetwater

Answer 23

In audio the fundamental is the frequency of the root, or core pitch making up a pitched sound. Except for a few special cases the fundamental is always the lowest frequency making up any pitched sound and is generally the strongest pitch we hear (in a strict Physics sense the fundamental is, by definition, the lowest pitch of a sound). Most sounds are comprised of a combination of a fundamental pitch and various multiples of it known as overtones. When overtones are added to the fundamental, which occurs in almost all naturally occurring sounds, the character of the sound is changed. The relationship between the fundamental and the overtones are what gives each sound its basic timbre. -sweetwater

Answer 24

Pronounced “tamber,” it is the subjective quality or tone color of a sound; the essential quality of a sound that makes it what it is. An oboe has a different timbre than a tuba, for example. Two oboes may have a slightly different timbre from one another. They sound different. Timbre is made up of all of the qualities of a sound: transient attack, harmonic content, envelope, overtone structure, and more. - sweetwater

Answer 25

The envelope of a sound can be explained as a variation that occurs to it over time. How a sound starts, continues, and disappears in terms of pitch, harmonic content, and loudness is a function of its envelope. An envelope generator is a circuit or algorithm found in most synthesizers that provide a means to apply these kinds of changes to a sound over time. -sweetwater

Answer 26

A harmonic sound is said to have a missing fundamental, suppressed fundamental, or phantom fundamental when its overtones suggest a fundamental frequency but the sound lacks a component at the fundamental frequency itself. The brain perceives the pitch of a tone not only by its fundamental frequency, but also by the periodicity implied by the relationship between the higher harmonics; we may perceive the same pitch (perhaps with a different timbre) even if the fundamental frequency is missing from a tone. For example, when a note (that is not a pure tone) has a pitch of 100 Hz, it will consist of frequency components that are integer multiples of that value (e.g. 100, 200, 300, 400, 500.... Hz). However, smaller loudspeakers may not produce low frequencies, and so in our example, the 100 Hz component may be missing. Nevertheless, a pitch corresponding to the fundamental may still be heard. -wikipedia

Answer 27

False. The more pulses in a sound wave, the higher the frequency and the higher the pitch.

Answer 28

We'd hear chords one note at a time with the higher pitches arriving first. (So it's good that amplitude/propagation and frequency are independent).

Answer 29

A compressor is a device that reduces the dynamic range of an audio signal. There are a variety of uses and applications for compressors, the most obvious one being to control the dynamic range of a live performance so that it will fit into the fairly narrow dynamic range of recorders, etc. Other applications include making a signal’s average level higher, increasing the apparent sustain on a guitar, evening out a vocal or bass guitar performance, fattening up sounds, and on and on. The list of possibilities is extensive! -sweetwater

Answer 30

A dynamics device whose function is to remove unwanted audio material below a certain threshold. Some type of “gain cell” is employed (usually a VCA) that can raise or lower the volume of the audio going through the unit. When the signal falls below a certain threshold that is set the gain cell will quickly drop the audio level down to a predetermined level. This level is usually very low, or even off, but in some applications it may only be a reduction of a few dB. The reason they are called gates is because when they “close” it sounds as if the audio has suddenly stopped, or has been “gated.” Now, it is possible to set many gates for slower response time so the effect is not as sudden, but often a sudden change is what is desired. Gates are often used on drum tracks to prevent bleed from other nearby drum mics, and they are sometimes used on noisy sources so when the desired audio signal stops the noise is automatically muted. The gated reverb sounds made popular by Phil Collins and Peter Gabriel in the 1980’s were the result of running a reverb’s decay through a gate. When the reverb level fell below a certain threshold the sound would abruptly cut off. -sweetwater

Answer 31

The opposite of a compressor. Where a compressor takes a given dynamic change and reduces it, an expander increases it, making changes larger. Expanders are used to “un-do” compression in some circuits (companding). More commonly, expanders are used for noise reduction. In this application (downward expansion), a threshold is set at a level below desired audio signals, but above the noise floor. When signal drops below the threshold, expansion is applied, pushing signal even further down, reducing the level of noise. For example, an expander might be set up with a 1:6 ratio. This means that for every 1 dB of input level change the expander sees, it will output a 6 dB change. When a signal drops below the threshold by 2 dB, the output of the expander will drop by 12 dB, similarly dropping the level of any background noise floor. -sweetwater

Answer 32

A limiter is a dynamics processor very similar to a compressor (see inSync WFTD 10/13). In fact, many compressors are capable of acting as limiters when set up properly. The primary difference is the ratio used in reducing gain. In a limiter, this ratio is set up to be as close to infinity:1 as possible (no matter how much the input signal changes, the output level should remain pretty much constant). The idea is that a limiter establishes a maximum gain setting, and prevents signals from getting any louder than that setting. Like compressors, limiters are used for a variety of applications. A few: Maximizing signal levels while preventing distortion when using digital recorders, preventing overload in a signal chain, setting a maximum volume level to protect users of in-ear monitors, protecting speakers and amplifiers from clipping, and so on. Any time you want to establish a maximum gain setting and prevent signals from passing it, a limiter is your tool of choice! -sweetwater

Answer 33

First a threshold is established. When the audio signal is louder than this threshold, its gain is reduced. The amount of gain reduction applied depends on the compression ratio setting. For example, with a 2:1 ratio, for every 2 decibels the input signal increases, the output is allowed to increase only 1 decibel. A variety of other parameters in the compressor will also affect its performance processing specific signals; attack time, release time and others are very important. -sweetwater

Answer 34

A parameter found on compressors, limiters and noise gates (and a variety of other dynamics-based processors), the threshold setting determines at what level the processor will begin working. For example, on a compressor, when signal level exceeds the threshold setting, it will be compressed; below the threshold signal will be passed unprocessed. On a gate, threshold determines the minimum input level required to cause the gate to open up and pass signal; when input level drops below the threshold, the gate will be closed preventing signal from passing. Carefully setting the threshold allows you to very specifically control when processing is being applied to a signal. -sweetwater

Answer 35

In a compressor, limiter, or expander, ratio is the amount of output level change that results from a given input level change. For example, in a compressor with a 4:1 ratio, an input level increase of 4 dB will result in an output increase of only 1 dB. An expander might have a ratio of 1:4; for a 1 dB input change, a 4 dB output change will result. Limiters typically have extremely high ratios, some claiming infinity:1, which essentially means that for virtually any input level increase, there will be only a very minor output level increase. -sweetwater

Answer 36

All three. Timbre is comprised of a multitude of frequencies. Partials are part of the timbre for a given instrument. Sine waves represent a single frequency. Since timbre is comprised of a multitude of frequencies, this means that timbre is also comprised of a multitude of sine waves.

Answer 37

Decrease the amplitude of the high frequencies.

Answer 38

Because it's a longitudinal (not transverse) wave.

Answer 39

1. Oscilloscope display 2. Spectrum analyzer 3. Spectrogram analyzer

Answer 40

1. Oscilloscope display 2. Spectrum analyzer 3. Spectrogram/Sonogram analyzer

Answer 41

On the spectrum analyzer display the horizontal shows the frequency and the vertical shows the amplitude. So we can see that this sound has a lot of energy at 2k or 1k or 500Hz and associating those numbers to the sound we hear. The problem is it is momentary and doesn't show us how things change over time.

Answer 42

The spectrogram analyzer is like the spectrum analyzer but repeated over time. So we get a sense of how the timbre, frequency and amplitude all change over time and most closely represents the way we hear.

Answer 43

Oscilloscope view

Answer 44

Oscilloscope

Answer 45

Exactly how the pressure is varying in the air or the voltage is varying in a wire.

Answer 46

The height of the waveform increases.

Answer 47

The number of repetitions (per second, assuming the zoom doesn't change) increases. For example going from one C to the next octave C doubles the frequency (repetitions over time).

Answer 48

the frequency of the pitch amplitude

Answer 49

A series of peaks, the largest at the fundamental and the others at multiples of the fundamental. The is called the harmonic series (which is a major function of timbre).

Answer 50

x= EQs | y=timbre

Answer 51

flipped on its side - instead of having frequency left to right frequency is up and down and time is going by slowly horizontally.

Answer 52

It changed color (from blue to green).

Answer 53

The Spectrogram/Sonogram shows X-Time Y-Frequency Z-Amplitude.

Answer 54

The harmonics changed depending on which vowel he was singing (for instance there was a gap around 1 khz when he was signing A and E but it was filled in for I and the pitch/harmonics changed while singing U because it has multiple sounds. The mouth is emphasizing and removing certain parts of the frequency range that is created by the vocal folds. The vocal folds would be like an oscillator/sound generator and the mouth is like a filter/EQ.

Answer 55

False Vowel sounds are primarily variations of SPECTRUM, not amplitude.

Week 1: Nature of Sound Flashcards

(81 cards)