Comd 3700 Exam 1 Lesson 4

Front 1

What is Psychoacoustics?

Back 1

Includes everything that can be perceived by the human ear from a sensory standpoint. This refers to how the sound “feels” to us.

Front 2

Describe Physical Acoustics

Back 2

Sound is the same with or without the human ear. Measurement is fixed/constant regardless of hearing loss type. Includes frequency, intensity and duration.

Front 3

Describe Psychoacoustics

Back 3

Requires the human ear and is the perception of sound. Each measurement of frequency, intensity and duration is perceived differently by each patient because of individual hearing differences.

Front 4

What is Pitch?

Back 4

Psychological measurement of whether a sound is high or low

Front 5

How is frequency related to pitch?

Back 5

Frequency, the physical measurement in Hz, or cycles per second, relates to the listeners interpretation of pitch, the psychological measurement of whether a sound is low or high.

Front 6

How is pitch measured (psych)?

Back 6

Mels measure pitch. A higher pitched sound will have more Mels, a lower pitched sound, less.

Front 7

What is a 1000 Mels?

Back 7

1000 Mels is the pitch of a 1000 Hz tone at a 40 dB sensation level for normal ears.

Front 8

What happens to pitch if you raise frequency?

Back 8

Raising the frequency of a sound makes the pitch higher.

Front 9

What happens to pitch if you Double frequency?

Back 9

Doubling the frequency raises the pitch one octave, but does not double the pitch.

Front 10

Loudness

Back 10

Subjective or psychological experience

Front 11

Phons

Back 11

Measure loudness ACROSS frequencies. Corresponds to loudness of a signal at other frequencies equal to intensity of 1000 Hz. 40 phons=40 dB SPL at 1000 Hz tone

Front 12

Sones

Back 12

Measure loudness UP frequencies. 1 sone=Loudness of a 40 db SPL at 1000 Hz tone. 1 sone=40 phones in normal ears.

Front 13

What we measure as Intensity the ear perceives as

Back 13

Loudness

Front 14

What we measure as Timber the ear perceives as

Back 14

Tonal quality

Front 15

We perceive a small increase in the intensity of a soft sound as a

Back 15

significant increase in loudness.

Front 16

We require a greater change in intensity to make a ____ sound louder than to make a ____ sound louder.

Back 16

loud, soft

Front 17

If we make a sound twice as intense, does it become twice as loud?

Back 17

This is not the case. Most auditory systems follow a power law, logarithmic concept.

Front 18

When we double the sound pressure of intensity, a ___dB increase occurs.

A threefold increase in sound pressure, 10 dB, _____ the loudness.

Back 18

6
doubles

Front 19

Assume a 1000 Hz pure tone. At 80dB SPL is ____ as loud as 70 dB SLP, and ____as loud as 90 dB SPL.

Back 19

twice, half

Front 20

Audiologists usually make 2 kinds of measurements....

Back 20

One is to test the ability of patients with possible disorders of the auditory system.
The other type is to measure the sound pressure levels in the environment.

Front 21

Audiometers—do?

Back 21

Test hearing of a person

Front 22

For the most part, every audiometer has the following:

(IF HE BE)

Back 22

1. Earphones-Supra-aural and/or insert earphones
2. Bone receiver
3. Hearing Level indicator or attenuator
4. Frequency Indicator
5. Ear Indicator.
6. Interrupter switch

Front 23

What frequencies does an audiometer test?

Back 23

125, 250, 500, 750, 1000, 1500, 2000, 3000, 4000, 6000 an 8000 Hz. Pure tones

Front 24

What is a simple audiometer?

Back 24

What is a simple audiometer?
A simple audiometer designed for pure tone testing only and is used as a screening audiometer.

Front 25

Interrupter switch

Back 25

Audiometer-this controls both when the test tone is on and the duration of the tone.

Front 26

Ear Indicator

Back 26

Audiometer-to select the ear to be tested, either left or right.

Front 27

Attenuator

Back 27

Audiometer-This controls the volume or intensity of each tone you present. This dial measures the volume, expressed in decibels Hearing Level or dB HL.

Front 28

Masking

Back 28

masking is the noise that's put in the non-test ear to keep it from hearing the test tone.

Front 29

What are the basic components necessary to deliver pure tone stimulus to a patients ear as shown in the Block Diagram of Audiometer?

Back 29

1. Generate a tone of given frequency. For instance, let's generate a tone at 1000 Hz.
2. Tone is delivered to an amplifier. Then the amplifier amplifies the tone to the maximum level. So if the audiometer is putting out 110 dB at the maximum level, that's the level at which the amplifier is producing the tones, 110 dB.
3. Attenuate the sound to the appropriate level. Water the sound down from 110 dB to 70, 30 or 10 db for example. The attenuator is the same as the hearing level dial.
4. Push the Interrupter/Silent switch to make the connection and deliver the tone.
5. Select either a bone conduction or air conduction as the mode of delivery of the stimulus.
6. You can also choose to have the tone delivered to the right earphone or the left earphone.

Front 30

What does it mean to Attenuate?

Back 30

Attenuate means to subdue or tone down or bring down. Just like if you have a bright color and it's attenuated by adding white to make it a softer color. This is what the dB dial on the Audiometer is actually doing. It is diluting the sound.

Front 31

When would you use a Diagnostic or Clinical Audiometer?

Back 31

In a clinic environment when you are conducting advanced testing, other than basic hearing screenings, then you will use a diagnostic or clinical audiometer for testing pure tones as well as speech testing. A speech audiometer is part of a clinical audiometer.

Front 32

What additional equipment does a Diagnostic/Clinical Audiometer contain?

Back 32

• Presentation Indicator-Changes the presentation of the tone from interrupted (normal choice) to pulsed, continuous, or warble tones
• Function Indicator-changes the audiometer function from microphone to air conduction, to bone conduction or to speech testing
• Microphone-Allows you to communicate with the patient while the headset occludes the ears
• Monitor-Important when you use a two-room test suite, a sound booth, or recorded speech tests
• Masking Control-produces a white or other noise to isolate an ear during certain tests
• CD Player (or tape player)-used for speech testing
• VU Meter-Monitors the input level by an averaging voltmeter called a Volume units or VU meter. The meter reads in dB VU, implying an electrical reference in watts.

Front 33

What is the objective of any pure tone audiometer?

Back 33

With any pure tone audiometer, the objective is to deliver a tone at given frequencies.

Front 34

What frequencies do we use to sample a person's hearing in audiometry?

Back 34

The lowest is 125 Hz. Then we go up in octaves (The difference between two tones seperated by a frequency ratio of 2:1). 250 Hz, 500 Hz, 1000 Hz, 2000 Hz, 4000 Hz until the high end at 8000 Hz.

Front 35

How do we test air conduction?

Back 35

When we are testing to determine type and severity we start the testing of the air conduction pathway using some type of earphone or rather a headset that consists of two earphones on an adjustable band that fits over the head.

Front 36

How are earphones color coded?

Back 36

Earphones are color coded, red for right ear and blue for left ear.

Front 37

How do we test bone conduction?

Back 37

A bone receiver on a spring steel headband is usually used to test the bone conduction pathway.

Front 38

Describe sound field testing and when it is used.

Back 38

There are times when we will test using the sound field of the audiometric suite or sound booth. This is usually done in speech testing. The signal is fed into the booth using loudspeakers, rather than earphones. If pure tones are used for testing in the sound field, then the stimulus of the sound must be changed to a warble, or wavy tone. When using a speaker output, the signal is fed to an auxiliary amplifier that creates additional power necessary to drive loudspeaker.

Front 39

What is a sound level meter?

Back 39

Sound level meters are instruments test airborne sounds to determine the sound pressure level in decibels.

Front 40

How is a sound level meter used?

Back 40

Sound level meter is used to test the level of airborne sound in factories, schools, offices, stores, airports, etc.
A sound-level meter can also be used to calibrate an audiometer.

Front 41

How does a sound level meter work?

Back 41

They will a) collect the sound energy from the surrounding environment, b) convert that energy to electricity, then c) give us a decibel readout as to the intensity of the sound in the surrounding environment.

Front 42

What kind of sound level meters are there and how big are they?

Back 42

Most sound level meters are battery operated and vary in size from half a loaf of French bread down to as small as a mouse you use on your computer. There are basic analog sound-level meters and sophisticated digital sound level meters.

Front 43

What are the components of a sound level meter?

Back 43

Frequency Hz Dial, Sensitivity Dial, Meter, Meter Stylus, Microphone, Microphone Diaphragm, Coupler

Front 44

Describe the function of a Frequency Hz Dial on a Sound Level Meter

Back 44

Can filter the frequency that you are only examining the sound energy/intensity at 1 frequency (eg: turn the frequency dial to 500 Hz and the meter will indicate what the sound intensity is in dB for 500 Hz)

Front 45

Describe the function of a Sensitivity Dial on a Sound Level Meter

Back 45

can adjust the sensitivity of the meter.

Front 46

Describe the function of a dB SPL Meter and its Styllus on a Sound Level Meter

Back 46

dB SPL Meter indicates if sound energy is present  Marked off in dB steps = – 1,2,3,4,5 and +1,2,3,4,5 
Meter Stylus = indicates on meter what the sound energy level is  In silence, meter indicator/stylus would drop tothe L side and nothing could be measured. When stylus is at 0 dB SPL, that means there is some sound energy coming in

Front 47

Describe the function of a Microphone on a Sound Level Meter

Back 47

converts acoustical energy into electricity. At top of sound level meter

Front 48

What does the Diaphragm of the earphone on a sound level meter do?

Back 48

Where is it located?
The diaphragm in the earphone over the opening of the ear canal causes a cavity to be formed. The diaphragm of the microphone sits atop the microphone between the microphone and the coupler.

Front 49

What goes on top of the Diaphragm of the sound level meter? Why?

Back 49

6 cubic centimeter coupler. Sound reacts to coupler/environmental size in predictable ways. When we put sound energy into a small cavity, the sound measured in that cavity is relatively large. If cavity size is increased, then sound pressure level in that cavity decreases. Walls of external auditory meatus, tympanic membrane, and earphone in a person’s ear, measure 6 cc on average. That is why a 6cc coupler is used to calibrate measurements on a sound level meter. Thus we use the 6 cc coupler when we do calibration measurements on a sound level meter.

Front 50

Why is calibration necessary?

Back 50

Calibration is necessary to determine if an audiometer is performing properly in terms of its acoustic output, attenuator linearity, frequency accuracy and harmonic distortion.

Front 51

How do you Calibrate an Audiometer?

Back 51

Use a Sound Level Meter to test and calibrate an Audiometer.

Front 52

How will a Sound Level Meter test and calibrate an Audiometer?

Back 52

An Audiometer measures hearing level. A sound level meter measures Sound Pressure Level. By converting results from Sound Pressure Level (from Sound Level Meter) to Hearing Level we can determine if an audiometer is calibrated correctly.

Front 53

Describe the Step-by Step process for calibration of an audiometer with a sound level meter.

(PP OOO RCD)

Back 53

1. Place Earphone from Audiometer on top of 6cc Coupler of Sound Meter
2. Put 500 gram weight on top of earphone.
3. On Audiometer, select 70 dB HL as the intensity of our output.
4. On Audiometer, select frequency in Hz (example 1000Hz)
5. On Sound Level Meter, place Sensitivity to 75 dB in anticipation of 70 dB tone coming from Audiometer
6. Read the meter. In the example, the SLM read +2.5
7. Calculate. In the example, 75 dB+2.5 dB=77.5 db SPL at 1000Hz
8. Determine if Audiometer is Calibrated correctly. Convert dB HL from audiometer to dB SPL on sound level meter. If they equal than audiometer is calibrated correctly.

Front 54

Why does 70 db HL equal 77.5 dB SPL?

Back 54

If you think back to the conversion we did from SPL to HL. We learned that at 1000 Hz you add 7.5 to convert dB HL to dB SPL. So, at 1000 Hz a 70 dB HL tone is equal to 77.5 dB SPL. This audiometer with this earphone is in perfect calibration. If we change frequencies and go to five hundred or 2000 Hz, we will have to look on our conversion chart from SPL to HL to see the difference there.

Front 55

What are the standard calibration procedures?

Back 55

1) use 500 g weight over the earphone. That pressure of the weight is a standard for calibration. If you increased or decreased the amount of weight put on top the earphone, sound level pressure would vary slightly.
2) Use 70 dB for output intensity on audiometer
3) Tolerance for intensity-allow up to 2.5 margin on either side of zero for meter reading on sound level meter. For a +2.5 dB error round up to + 5dB (strong). For a -3.0 dB error, round down to -5 dB (weak).
4) Tolerance for Frequency-Calibration results will provide confidence in the calibration within 3 (or 300 Hz) to 5% of testing frequency.

Front 56

Why do you put a 500-gram weight atop the earphone?

Back 56

That pressure of the weight is a standard for calibration. If you increased or decreased the amount of weight put on top the earphone, sound level pressure would vary slightly.

Front 57

What are the tolerance levels when calibrating?

Back 57

In terms of intensity, the standard allows us plus or minus 2.5 dB margin of error. If we come up with 2.5 on either side of our desired level, we move to the next whole 5 dB.
With frequency, our tolerance is somewhere between three and five percent, depending on the frequency

Front 58

Explain how you would correct calibration differences when testing?

Back 58

You would note the strong-weak dB and put that on a correction chart so the next person who did testing with the audiometer understood that the audiometer was not in perfect calibration. It would specify that in fact, we were strong by 5 dB or weak by 5 dB or some other dB level.

Front 59

If the audiometer is not calibrated perfectly at zero, how do we adjust the final result on the hearing chart before we report the patient's hearing to someone else?

Back 59

You would obtain the client's threshold on the audiometer. Then add or subtract the number on the correction chart and put that amount on the audiogram.