Exam 2

Which can an average normal hearing listener discriminate: a 500 Hz tone at 0 degrees vs 2 degrees azimuth or the same sound at 80 degrees vs 82 degrees azimuth?

0 vs 2 degrees. *Rule of thumb in notebook*

Can most listeners discriminate at 1000 Hz tone from a 1001 Hz tone at 40 dB SL? Why or why not?

0.002 x 1000 Hz = 2 Hz. The average normal hearing adult can just barely hear the difference between 1000 and 1002 Hz. 1000 vs 1001 Hz is a smaller change; therefore, most listeners would not be able to discriminate this change.

Alicia can just barely discriminate between a 200 ms temporal interval and a 215 ms temporal interval. Are her temporal interval discrimination abilities better, worse, or the same as an average normal hearing young adult?

0.1 x 200 ms = 20 ms. The ANHYA can hear 200 vs. 220 ms. Alicia needs a smaller change to be able to hear it, making her abilities better.

The signal is a 3000 Hz tone. Rank the following maskers from least to most masking (ties are okay): A) The masker is a narrowband noise centered at 3000 Hz with a bandwidth of 200 Hz. B) The masker is a narrowband noise centered at 3000 Hz with a bandwidth of 350 Hz. C) The masker is a narrowband noise centered at 3000 Hz with a bandwidth of 600 Hz.

0.1 x 3000 = 300 Hz (CB is between 2850 to 3150 Hz) Least: 200 Hz. Most: tie because they both fill the entire CB. *Rule of thumb in notebook*

Rank order the three dimensions of sound localization from best human perceptual abilities to poorest.

1. Azimuth. 2. Front/back. 3. Distance and range.

Thresholds will be better (lower) for which of these: A) a 1000 Hz, 50 ms tone B) a 1000 Hz, 100 ms tone

100 ms tone will be easier to detect (lower threshold). For detection, as you make the sound longer, thresholds improve up to a duration of about 200 ms (critical duration). Signal detection sensitivity increases with increasing duration. For signals < 200 ms: 10x duration change = 10 dB difference in thresholds.

What is twice as loud as 50 sones?

100 sones. *Rule of thumb in notebook*

How much louder is 12 sones compared to 3 sones?

12 sones is 4 times as loud as 3 sones.

What sound is 8 times louder than 2 sones?

16 sones

How much louder is 50 phons vs 30 phons?

2 x 2 = 4

A average normal-hearing young adult can just barely detect a ________ __________ gap in broadband noise at 50 dB SL.

2-3 ms.

You have two broadband noises. One is modulated at a rate of 20 Hz and the other is modulated at a rate of 200 Hz. Which, if either, has a pitch?

20 Hz has no pitch. 200 Hz has a pitch.

A 6000 Hz tone is played 25 ms before a 50 dB masker. The amount of masking is 35 dB. If I increase the masker level by 10 dB, how much dose the amount of masking increase?

3 dB

Approximately how many sones is a 60 phon sound (use rule for sound over 30 phons)?

4 sones.

How many dB of masking is there is a listener's threshold of audibility for a 3000 Hz tone is 10 dB HL and their threshold for the same tone in a 60 dB SPL white noise is 42 dB HL?

42 - 10 = 32 dB

The following graph shows the psychometric function for one listener's ability to detect a tone in quiet. If we define threshold at 50% point, approximately what is this listeners' threshold?

5.25 dB SPL (find 50% on the y-axis and follow it across to the curve, then find the corresponding value on the x-axis).

Here is a partial audiogram for a listener with both hearing loss and recruitment. Based on the audiogram, what is this listener's dynamic range (dB between threshold of audibility and threshold of discomfort) at 8000 Hz?

50 dBHL - 110 dBHL; which is a 60 dB dynamic range.

Madeline can just barely discriminate between a 400 ms temporal interval and a 410 ms temporal interval. Are her temporal interval discrimination abilities better, worse, or the same as an ANHYA?

50-500 ms = 10% (0.1) change (5-50 ms) 0.1 x 400 ms = 40 ms; this means that an ANHYA can hear 400 vs 440; Madeline needs smaller change to be able to hear it, her abilities are better.

What twice as intense as 50 dB SPL?

53 dB SPL

I am trying to talk to a student on my computer whose voice is at 55 dB SPL. My children are happily playing in the background at 70 dB SPL. Assuming that the student is the signal and my children are the masker, what is the signal-to-noise ratio (in dB)?

55 - 70 = -15 dB

What has twice the pressure as 50 dB SPL?

56 dB SPL

If I play a 50 dB SL tone in one ear and then play the same tone in both ears, how many dB more intense does it sound when played in both ears?

6 dB louder.

If the modulation rate of a noise is 30 Hz, how much of a change in amplitude (what AM depth) will be required for an average normal hearing young adult to detect the amplitude modulation?

6%. *Rule of thumb in notebook*

In which case is there more masking: a 1000 Hz signal tone is presented 60 ms after a broadband noise masker or the same signal is presented 60 ms before the same masker?

60 ms after has more masking.

In which case is there more masking: a 1000 Hz signal tone is presented 60 ms after a broadband noise masker or the same signal is presented 90 ms after the same masker?

60 ms has more masking.

What is the loudness of a 4 sone sound in phons?

60 phons

What is twice as loud as 50 phons?

60 phons.

Which sound would be easier to localize in elevation: a 500 Hz tone or 7000 Hz tone?

7000 Hz tone. *Rule of thumb in notebook*

What is twice the loudness of 4 sones?

8 sones. *Rule of thumb in notebook*

Which sound is easier to localize in elevation/front/back: a 2500 Hz tone or an 8000 Hz tone?

8000 Hz is easier. *Rule of thumb in notebook*

The masker is a 45 dB SPL noise with a bandwidth of 100 Hz centered on 200 Hz. Which, if either, of the following signals would be masked more? A) 500 Hz tone. B) 8000 Hz tone.

8000 Hz tone. *Rule of thumb in notebook*

Which sound would be masked more by a noise with a bandwidth of 700 Hz centered at 7000 Hz? A) a 3000 Hz tone B) a 6000 Hz tone

A 6000 Hz tone. *Rule of thumb in notebook*

Can an ANHYA discriminate between a 1500 Hz and a 1503 Hz tone presented at 40 dB SPL?

ANHYA can hear a 0.002 change in frequency. 0.002 x 1500 = 3 Hz So yes.

My nephew James who is 9 years old, can just barely detect a 5 ms gap in an ongoing broadband noise (40 dB SPL). Are his gap detection abilities better, worse or the same as an ANHYA?

ANHYA can hear a gap in a sound of about 2-3 ms in a broadband noise of 40 dB SPL or above. Therefore, James gap detection abilities are worse than ANHYA.

How many dB of masking are there if a listener's threshold of recognizing speech is 5 dB HL in quiet and 30 dB HL in the presence of broadband noise?

Amount of masking = threshold in masker - threshold in quiet. 30 dB HL - 5 dB HL = 25 dB

Explain the answer from previous question.

Critical bandwidth is 0.1 x 1000 = 100 Hz; the tone has a bandwidth of only 1 Hz and so doesn't fill the critical band. A noise with energy from 700 to 1300 Hz has a lot more energy in that 10% masker frequency than a single frequency of 1005 Hz. *Rule of thumb in notebook*

You play three 1500 Hz tones at 30 dB to a listener. They differ only in duration: 100 ms, 300 ms, 500 ms. Rank the stimuli from easiest to hardest to detect (ties are okay).

Easiest: tie between 300 ms and 500 ms because they are both 200 ms or higher. Hardest: 100 ms.

The signal is a 1000 Hz, 60 dB tone. Rank the following maskers from least to most masking (ties are okay): A) 500 Hz, 80 dB B) 1010 Hz, 80 dB C) 2000 Hz, 80 dB

From least to most masking: 2000 Hz, 500 Hz, 1010 Hz. *2 Rule of thumbs in notebook*

EXAMPLES FROM:

GROUP HELP HOURS

In backward masking, does the signal come before or after the masker?

In backward masking, the signal comes BEFORE the masker and the masker has to travel BACKWARD in time in order to mask it.

You are given a 75 dB SPL tone complex with energy at 3500, 4000, and 5000 Hz. Give one example of how you could DECREASE the pitch of the tone complex by changing the intensity.

Increase the intensity because pitch goes down with increasing intensity below 1000 Hz.

Which sound is easier to localize in azimuth: a 2000 Hz tone or a 6000 Hz tone? Why?

It is much harder to localize in azimuth when the sounds are between 800 and 3000 Hz because we switch from using predominately IPD at low frequencies to ILD at higher frequencies, and ILDs are best above 3000 Hz. We localize best (fewest errors) below 800 Hz and above 3000 Hz.

Which of the following masks a 1000 Hz tone more: a 1005 Hz tone or a noise with energy from 700 to 1300 Hz?

More masking by a noise with energy from 700 to 1300 Hz.

In which case is there more masking: a 1000 Hz signal tone is presented 75 ms before a broadband noise masker or the same signal is presented 75 ms after the same masker?

More masking when a 1000 Hz signal tone is presented 75 ms after a broadband noise masker. *Rule of thumb in notebook*

In which case is there more masking: a 1000 Hz signal tone is presented 80 ms after a broadband noise masker or the same signal is presented 100 ms after the same masker?

More masking when the 1000 Hz signal tone is presented 80 ms after the broadband noise masker. *Rule of thumb in notebook*

The signal is a 2000 Hz tone. Rank the following maskers from most to least masking (all at 70 dB): a 2005 Hz tone, 1000 Hz tone, and 4000 Hz tone.

Most: 2005 Hz tone. Middle: 1000 Hz tone. Least: 4000 Hz tone.

In which case is there more masking: a 1000 Hz signal tone is presented immediately after a broadband noise masker or the same signal is presented immediately before the same masker?

No delay - more masking when the signal is before the masker.

A broadband noise is amplitude modulated at a rate of 500 Hz. Does it have a pitch?

No, because it would need to be modulated at a rate of 70 - 400 Hz to have a pitch.

You are presented with the following two sounds: a 50 Hz pure tone at 30 dB SPL and a 2000 Hz pure tone at 20 dB SPL. How will the loudness of these two tones compare? (Given a graph)

Only the 2000 Hz, 20 dB pure tone is audible, so it is impossible to compare its loudness to the (inaudible) 50 Hz, 30 dB tone.

How to apply these rules of thumb?

Pitch goes up with increasing intensity at 3000 Hz and above. Pitch goes down with increasing intensity at 1000 Hz and below. Pitch unchanged with intensity change if frequency is between 1000 - 3000 Hz.

What is the absolute difference limen if the relative difference limen is 0.05 and the reference tone is 3000 Hz?

Rel DL = Abs DL / ref 0.05 x 3000 Hz = 150 Hz

Determine the relative difference limen if the absolute change in signal frequency that the listener can discriminate is 10 Hz and the reference tone is 1000 Hz.

Rel DL = Abs DL / ref 10 / 1000 = 0.01

Determine the relative difference limen if the absolute change in signal frequency that the listener can discriminate is 50 Hz and the reference tone is 4000 Hz.

Rel DL = Abs DL / ref 50 Hz / 4000 Hz = 0.0125

Katrina can just barely discriminate between a 300 ms temporal interval and a 324 ms temporal interval. Are her temporal interval discrimination abilities better, worse, or the same as an average normal hearing young adult?

Rel DL = Abs DL / ref Rule of thumb: 0.1 24 / 300 = 0.08 ms; this proportion is lower than the rule of thumb so Katrina is better than an average normal hearing young adult.

What is the absolute difference limen if the relative difference limen is 0.02 and the reference tone is 4000 Hz?

Rel DL x ref = Abs DL 4000 x 0.02 = 80 Hz

The masker is a 30 dB SPL narrowband noise with energy from 1000-1050 Hz. The signal is a 60 dB SPL, 1700 Hz tone. What is the signal-to-noise ratio?

SNR = signal level - noise level SNR = 60 dB SPL - 30 dB SPL = 30 dB

If two sounds are identical, except one reaches full intensity faster than the other, do they have the same pitch? The same timbre?

Same pitch, because onset and offset of amplitude envelopes don't affect pitch. Different timbre, because onset and offset of amplitude envelopes does effect timbre.

Two complex tones are identical except that one is missing the fundamental frequency. Is the pitch of the two sounds the same or different?

Same; as long as the calculated f0 is the same, the pitch is the same, it doesn't matter whether the fundamental is present or not.

Is the dynamic range smaller or larger than you'd expect for a normal-hearing listner?

Smaller.

If sound A is 90 phons and sound B is 70 phons, how much louder is sound A than sound B?

Sound A is four times louder than sound B. *Rule of thumb in notebook*

You are presented with the following two sounds: a 100 Hz pure tone at 40 dB SPL and a 1000 Hz pure tone at 40 dB SPL. How will the loudness of these two tones compare? (Given a graph)

The 1000 Hz pure tone is louder than the 100 Hz pure tone.

You are presented with the following two sounds: a 200 Hz pure tone at 70 dB SPL and a 9000 Hz pure tone at 70 dB SPL. Which, if either, tone is louder? (Given a graph)

The 200 Hz tone at 70 dB SPL is louder, because it has about 71 phons loudness level, whereas a 9000 Hz tone at 70 dB SPL has about 64 phons.

What is the width of the critical bandwidth centered on a 1800 Hz tone? Unit is Hz.

The critical bandwidth is 10% of the signal frequency. 0.1 x 1800 = 180 Hz.

At moderate intensities, a listener's intensity discrimination threshold is measured to be 3 dB for wide-band noises. This means that?

The listener can just differentiate between two noises, at moderate intensities, differing by 3 dB.

Does the listener in the previous question (just differentiate by 3 dB) have better or worse sensitivity to intensity change than the ANHYA? Why or why not?

The listener has worse sensitivity because absolute difference limen for wide-band noise is around 1 dB for the average listener.

The signal is a 500 Hz tone. In which case is there more masking? A) the masker is a narrowband noise centered at 500 Hz with a bandwidth of 5 Hz. B) the masker is a narrowband noise centered at 500 Hz with a bandwidth of 25 Hz. C) masking will be the same in both cases.

The masker is a narrowband noise centered at 500 Hz with a bandwidth of 25 Hz. *Rule of thumb in notebook*

How will the pitch of a very intense 250 Hz tone compare to the same pure tone at a more moderate intensity?

The pitch of the more intense tone will be lower. *Rule of thumb in notebook*

Which has a higher pitch: 200 Hz tone at 50 dB SPL or 200 Hz tone at 90 dB SPL?

The rule that applies is: pitch goes down with increasing intensity at 1000 Hz and below, so the 50 dB SPL tone is higher in pitch.

Which has a higher pitch: 2000 Hz tone at 50 dB SPL or 2000 Hz tone at 90 dB SPL?

The rule that applies is: pitch is unchanged with intensity change if frequency is between 1000 and 3000 Hz. Both sounds have the same pitch.

Which has a higher pitch: 6000 Hz tone at 50 dB SPL or 6000 Hz tone at 90 dB SPL?

The rule that applies: pitch goes up with increasing intensity at 3000 Hz and above, so the 90 dB SPL tone has higher pitch.

The masker is an 80 dB narrowband noise with a bandwidth of 200 Hz centered on 2000 Hz. In which of these situations would there be more masking? A) the signal is a 16,000 Hz tone. B) the signal is a 250 Hz tone. C) they would both be equally masked

The signal is a 16,000 Hz tone. *Rule of thumb in notebook*

Which is easier to detect: a 10 ms, 1000 Hz tone presented immediately before a broadband masker or the same 10 ms, 1000 Hz tone presented immediately after the same masker?

There is less masking/easier detection when the signal is immediately after the masker. *Rule of thumbs in notebook*

If two sounds are identical, except that one has components at 1000, 2000, 4000, and 8000 Hz and the other has components at 1000, 3000, 5000, and 6000 Hz, do they have the same pitch? The same timbre?

They have the same pitch, but different timbre.

Thresholds will be better (lower) for which of these: 1) a 1000 Hz, 250 ms tone. 2) a 1000 Hz, 400 ms tone.

Thresholds should be the same for both. *Rule of thumb in notebook*

In simultaneous masking, if the masker level increases by 10 dB, how much does the amount of masking increase? In forwards masking, if the masker level increases by 10 dB, how much does the amount of masking increase?

We increase the amount of masking by the same amount: if masker level increases by 10, the amount of masking increases by 10 dB. We increase the masker level by 10 dB, the amount of masking increases by 3 dB. *Rules of thumb in notebook*

Perceptually speaking, we make the most errors in horizontal localization when signals are in what frequency range? Give two reasons.

We make the most errors in the frequency range of 800 - 3000 Hz. This is because when we switch from IPD dominance (<1600 Hz) to ILD dominance (>800 Hz), we have the poorest perception. IPD is good in the range below 1600 Hz, but ILD is not good in that range - best above 3000 Hz.

What cue(s) doe people differentiate between sounds located at paired (i.e. front/back) angles in azimuth (horizontal)? An example of paired angles would be 45 degrees and 135 degrees because they are both 45 degrees from the midline of the head (0 degrees is midline in front and 180 degrees is midline in back).

We would use monaural cues because the distance between the two ears is the same, but our ears face forward and we use those pinna cues to discriminate between sounds.

If I play a 50 dB SL tone in one ear and then play the same tone in both ears, how many dB more intense does it sound when played in both ears?

When played in both ears, the 50 dB SL tone would sound 4x as intense than how it would sound in one ear. 4x intense = 6 dB more intense.

Imagine you are presented with a very intense 7000 Hz tone and the same pure tone at a more moderate intensity. Which, if either, tone is higher in pitch?

When the sound is at 3000 Hz and above, pitch increases as intensity increases. The more intense sound will have a higher pitch. *Rule of thumb in notebook*

If a broadband noise is amplitude modulated at a rate of 200 Hz, does it have a pitch?

When there is a modulated frequency between 70 - 400 Hz, there is a pitch, so yes it has pitch.

How wide is the critical band centered on 2500 Hz? Give the range of frequencies that are in this band.

Width of critical band = 0.1 x signal frequency. 0.1 x 2500 Hz = 250 Hz 250 / 2 = 125 2500 + 125 = 2625 2500 - 125 = 2375 Critical range: 2375 - 2625 Hz

Can most normal hearing young adults discriminate a 40 dB broadband noise from a 42 dB broadband noise?

Yes. *Rule of thumb in notebook*

If I have a 30-ms, 2000 Hz tone, does that tone have a pitch?

Yes. *Rule of thumb in notebook*

Can an average normal-hearing young adult discriminate between a 500 Hz and a 501.5 Hz tone presented at 40 dB SL?

Yes. 0.002 x 500 = 1 Hz; can barely hear a difference between 500 and 501. *Rule of thumb in notebook*

If I have a 10 ms, 3000 Hz tone, does that tone have a pitch?

Yes. Pitch percept begins to emerge when a sound is: <1000 Hz, 3-9 periods long. ≥ 1000 Hz, 10 ms long.

You are given a 40 dB SPL complex tone with energy at 1200, 2400, and 3600 Hz. Describe one way that you could DECREASE the pitch of this tone by changing one of these frequencies.

f0 = 1200 Hz; anything change that lowers the f0 will lower the pitch. Change 1200 Hz to 600 Hz, which would change the f0 to 600 Hz.

If a complex sound has frequency components of 2500 Hz, 3750 Hz, and 5000 Hz, it will have the same or very similar pitch to what pure tone?

f0 = 1250 Hz. The sound will have a pitch similar to a pure tone at 1250 Hz.

What is the absolute difference limen if the relative change in the signal frequency is 8% and the magnitude of the reference tone is 800 Hz?

rel DL = delta f / f = ((0.08(800)) / 800 = 0.08 Abs DL = rel DL x ref 0.08 x 800 = 64 Hz