SLHS 302 Final questions

Objective vs. Subjective measures

Objective measures -e.g. threshold, JND - task has a right or wrong answer Subjective measures -e.g. loudness, pitch - no right or wrong answer, it's your perception

You are flying with a cold, and so your Eustachian tube is not functioning well. Which of the following might you experience while flying?

Pain and Reduced hearing sensitivity

Sensorineural hearing loss

Part: Inner ear Causes/Type: -ototoxis drugs (antibiotics or cancer drugs) -damage to hair cells -presbycusis (age-realted HL)

Conductive hearing loss

Part: outer and middle ear Causes/Type: -cerumen (buildup of ear wax) -otitis media (ear infection) -otosclerosis -damage to ossicles Treatment: surgery, hearing aids (amplification) --> easiest to overcome

Physical or Perceptual? Loudness

Perceptual

Physical or Perceptual? Pitch

Perceptual

Physical or Perceptual? Timbre

Perceptual

Physical or Perceptual? Duration

Physical

Physical or Perceptual? Energy

Physical

Physical or Perceptual? Frequency

Physical

Physical or Perceptual? Intensity

Physical

Physical or Perceptual? Power

Physical

Assume that the telephone system acts as a perfect (ideal) bandpass filter with cutoff frequency of 400 and 3400 HzFor a female speaker creating a periodic speech sound of F0=200 Hz, what happened to the voice pitch at the output?

Pitch does not change, but the timbre does

Based on the normal-hearing and hearing impaired loudness function, what must a hearing aid do to overcome the effects of loudness recruitment?

Provide high gain for soft sounds and low gain for loud sound.

Resolved or Unresolved? Greatest pitch salience (strength)

Resolved harmonics

Resolved or Unresolved? Low-frequency harmonics

Resolved harmonics

Resolved or Unresolved? Spectral theory for pitch

Resolved harmonics

Resolved or Unresolved? Which provide stronger pitch?

Resolved harmonics

What type of hearing loss would be considered synapses (damage)?

Sensorineural hearing loss

Basilar membrane

The basilar membrane has a traveling wave motion excited by the the stapes. The stapes and fluid will move differently for each stimulus in the cochlea. -Place of vibration depends on frequency of stimulation -Remember that the base is stiffer than the apex and responds best to high frequencies -sound always travels from base to apex

Consider a pulse train. If the time interval between the pulses is decreased (so the pulses occur more rapidly) what happens to the spectral properties of the sound?

The harmonics get further apart *time domain getting larger, the frequency domain will do the opposite

Upward Spread of Masking

The upward spread of masking can be explained by the asymmetry of the traveling-wave response pattern on the basilar membrane. E.g., the response pattern for a 100-Hz masker overlaps significantly with the 200-Hz signal place (peak of 200-Hz response pattern), and thus there is more masking when the masker is below the signal (M<S). In contrast, the response pattern for a 200-Hz masker overlaps much less with the 100-Hz signal place (peak of 100-Hz response pattern ), and thus there is less masking when the masker is above the signal (M>S).

Resolved or Unresolved? High-frequency harmonics

Unresolved harmonics

Resolved or Unresolved? Temporal theory for pitch

Unresolved harmonics

CNS origins of ABR Waves I-V

Wave I: Auditory Nerve Wave 2: Cochlear Nucleus Wave 3: Superior Olivary Complex Wave 4: Lateral Lemniscus Wave 5: Inferior Colliculus

How can you benefit from having two ears?

You can detect up to ~15 dB of a signal in noise (amplification). And you can localize sounds better

Tone (pitch) height

a sound quality corresponding to the level of pitch. tone height is monotonically related to frequency

Tone (pitch) chroma

a sound quality shared by tones that have the octave interval

When are interaural cues not super helpful?

cone of confusion and mid frequency sources

Harmonics

integer multiples of the fundamental frequency F0=125 1st: 125 x 1 = 125 2nd: 125 x 2 = 250 3rd: 125 x 3 = 375

Graph asking what the critical bandwidth is

it will be where the change is, the point (the number on x axis bottom)

If the ear canal was larger than it is now, what would happen?

then it will be more sensitive to low frequencies

Know the tone duration: Temporal Integration

-The process by which a sound at a constant level is perceived as being louder when it is of greater duration -Generally, as a sound gets longer, it becomes easier to hear (up to ~300 msec) -Suggests that the human auditory system can temporally integrate (add up) energy, but only up to ~300 msec * double duration is 3 db (100-200 ms, energy: you'll add) 3 db for every doubling ○ Threshold is when you decide whether it is worse or better - longer, subtracting. Shorter - adding

Weber Fraction -- Frequency: What is Weber's fraction at 2000 Hz? What frequency range does Weber's fraction hold?

0.002 because you look at the graph 500-2000 because that is where it gets flat on the graph

Loudness Recruitment

Abnormal growth of loudness. - happens for patients with sensorineural hearing loss. Cochlear Hearing Loss: elevated thresholds normal loudness at high sound levels Results in: steeper loudness growth Reduced dynamic range of hearing (in dB SPL)

Resolved harmonics

Because apical (low-frequency) filters have small bandwidths, they only pass individual harmonics (pure tones) This allows spectral theories to work well for low harmonic numbers Provide the most-salient (best) pitch percept.

Unresolved harmonics

Because basal (medium-high frequency) filters have larger bandwidths, they pass several harmonics (which interact to create modulations; periodicity at F0) This allows temporal theories to work well for medium-high harmonic numbers But a less salient pitch

Octaves

Doubling of Frequency. Fundamental frequency x 2 = 1st. 1st x 2 = 2nd

Retrocochlear hearing loss

Part: after cochlear Causes/Type: -tumor in the wave I-V

Cues to segregating sound source

Spectral separation Spectral profile differences Harmonicity Spatial separation Temporal separation Temporal onsets and offsets Temporal modulations

What frequencies are relevant for stiffness, mass, and damping

Stiffness: Low Frequencies Mass: High Frequencies Damping: Medium Frequencies

Wavelength

distance traveled in one cycle (meters) -know equations and how to calculate

Typical frequency range of human hearing

young people: 20-20,000 Hz by college age: 20-15,000 Hz -perceptual dynamic range is thus ~120 dB

Destructive interference

(cancellation): two wave of a different sign -they CANCEL to create a smaller pressure

In some situations the threshold of a signal tone masked by a noise masker is lower when the noise is on continuously and the tone is turned on and off than when the noise and tone are turned on and off together. What characteristics of sound source determination may help explain this difference in masked threshold?

*The onset and offset cues. - onset is part of a sound during which amplitude increases. - offset is part of a sound during which amplitude decreases *Or moving the masker or signal off the midline

If a 25 dB SPL tone is increased in duration from 50 ms to 800 ms, how does the energy in tone change?

+12 dB

What is the critical ratio (CR) estimated of the auditory filter bandwidth (in Hz) if signal power at threshold is 65 and the spectrum level of the broadband masking noise is 35 dB/Hz?

- 65-35=30 - 10log(x) = 30 (i.e., 10^(30/10) - x=1000 Hz

Assume the human ear can perfectly integrate energy across time up to 300 ms. If detection threshold for a 50-ms tone is 25 dB SPL, then how would the detection threshold change if the time was increased in duration to 200 ms?

-6 dB

Double distance

-6 dB

Sound localization

-Cone of confusion: A region of positions in space where all sounds produce the same ITDs and ILDs . *overcome: HRTF, Turning the head -Mid frequencies are not as good

Duplex theory of localization

-ITDs used at low frequencies -ILDs used at high frequencies -it is difficult to accurately localize sound sources with mid frequencies because there are only two cues for determining location

What are the three localization cues?

-Interaural level differences *sound shadows are most prominent at high frequencies *significant ILD exist for higher frequencies *physiology = Lateral superior olive (LSO) -Interaural time differences *most prominent at low frequencies *Azimuth *physiology: medial superior olive (MSO) -Spectral cues *most prominent as direction-dependent spectral notches at high frequencies *Head-Related Transfer Function

How can we use pitch?

-Melody of a song -Gender and age (adult/child) of a talker -Segregating multiple talkers (e.g. two male speakers will have slightly different pitch) -Prosodic information (e.g. rising intonation for questions). -Word meaning in tonal languages (e.g. Mandarin Chinese).

Binaural Masking

-Monotic: stimuli presented to only one ear -Diotic: identical stimuli presented to both ears, or no interaural differences for the signal and the masker presented to each ear. -Dichotic: different stimuli presented to the two ears *REMEMBER: "ch" in dichotic is for "change" between the two ears *signal and masker same, poor signal detection *signal and masker different, good signal detection

Spectral Theory

-Pitch can be estimated from the frequency spacing of harmonics -Even if the fundamental (or other sets of harmonics) are missing, this can still work by finding the best F0 to match the harmonic spacing.

Temporal Theory

-Pitch can be estimated from the temporal periodicity of complex sounds -Temporal periodicity is unaffected by missing fundamental, so this can work.

If a patient has a threshold of 20 dB SPL at 500 Hz and the ANSI standard is 4 dB SPL, What is their threshold in dB HL? Is this considered normal?

16 dB HL. Yes, it is less than 20

For the tones (2000Hz and 2500Hz), which tone will provide more masking of the other

2000 Hz

Which musical note has the closest tone chroma to a musical note played at 512 Hz?

256 Hz (octave)

At 4kHz the ANSI standard threshold is 5.5 dB SPL. As an audiologist, you determine a listener's threshold at 4 kHz to be 35 dB SPL. What is their threshold in dB HL?

29.5 dB HL -dB HL = listener's threshold in dB SPL - ANSI standard -the higher the threshold (above 0 dB HL), the worst their hearing is, although "normal" limits are generally considered to be 0 - 20 dB HL

Based on the temporal modulation transfer function (TMTF) showing detection threshold as a function of modulation frequency, at which modulation frequency is easiest to detect the presence of modulation?

4 Hz

Consider a computer with a cooling fan that produces broadband noise at an intensity level of 42 dB SPL. If seven additional computer fans are added to make 8 in total, what will the final intensity total fan output, in dB SPL?

51 dB SPL (3 doublings, increase of 3 dB, 9 in total)

What testing do you do in the clinic to determine whether a person has a conductive or sensorineural hearing loss?

Bone conduction

Constructive interference

Both are positive or both are negative -they ADD to create greater pressure

What type of hearing loss would be easiest to overcome with hearing aids?

Conductive, lessening amplification

If you have a filter with cutoff frequencies, what happens to frequency?

Falls outside of the range, it will be removed. If it is within the range, stays the same

After a loud noise exposure, if your audiometric thresholds return to normal within 2 weeks, your auditory system has not been damaged. True or False?

False (Hidden hearing loss TTS can cause permanent damage)

Which frequencies are affected by the head shadow?

For frequencies above 1000 Hz, the head blocks some of the energy reaching the opposite ear

How to find Fundamental Frequency (Hz) and repeat time(s) if you're given a series of harmonics

Fundamental Frequency = fine the greatest common factor Repeat time = take (1/Fundamental Frequency)

If frequency of a sound source is reduced by half, what happens to wavelength?

It doubles. Speed does not change

For what type of anatomical hearing loss would a cochlear implant be needed?

Loss of Inner Hair Cells

Know different filters and what they look like in a graph

Low Pass Filter High Pass Filter Band Pass Filter Band Reject Filter

Converting units

1 sec = 1000 ms 1 kHz = 1000 Hz 1 m = 100 cm = 1000 mm 1 cps = 1 Hz

The difference between critical ratio, critical bands, and notch noise tone detection. Which one is more reliable for auditory filter band width detection?

1) Critical ratio (CR): In the case of tone detection in broadband noise, we saw: Detection occurs at a fixed signal-to-noise ratio, SNR (dB) = Ps (dB) - PN (dB) Often assumed that detection occurs for equal signal (Ps) and noise power (PN) through the filter, i.e., SNR = 0 dB, thus Ps (dB) = PN (dB), where PN (dB) = TPN:AF (dB) = N0 (dB/Hz) + 10log (BWAF) This means the auditory-filter BW can be estimated as 10log (BWAF) = Ps (dB) - N0 (dB/Hz), which has been referred to as the critical ratio (CR) 2) Critical band (CB): In the case of tone detection in narrowband noise, we expect When the noise BW (BWN ) is smaller than the auditory bandwidth (BWAF), masking will increase as BWN gets bigger ... until BWN = BWAF For BWN > BWAF, masking will be constant since the "filter is full" Thus, the "critical bandwidth (CB)" can be estimated experimentally by finding the noise bandwidth at which further increases do not increase masking 3) Notched-Noise , Equivalent Rectangular Bandwidth (ERB): Varying the notch width of band-reject noise varies the amount of noise within the auditory filter and thus controls the amount of masking (wider notch width, less noise, less masking) Detection thresholds measured as a function of notch width Derive best filter to predict the detection thresholds Typical summary metric is ERB (i.e., the BW of a rectangular filter that passes the same noise power as the actual (~rounded) auditory filter * Notch noise tone detection is more reliable

Temporal Integration: Assume the human ear can perfectly integrate energy across time up to 300 msec. If detection threshold for a 50-ms tone is 30 dB SPL, then what would be the detection threshold for a 100-ms tone? For a 12.5-ms tone?

100-ms tone is twice as long, so you need half as much power (P=E/T), which corresponds to a 3-dB reduction (energy and power means you use 10*log10(1/2) = -3 dB. So, detection threshold would be 30 dB SPL - 3 dB = 27 dB SPL. Likewise, a 12.5-ms tone is one-fourth as long, so you need four times the power, or 6 more dB, so detection threshold is 36 dB SPL. *getting longer, threshold would decrease. Getting shorter, threshold would increase (always with 3 because it is time)

What are the three types of hearing loss?

-conductive -sensorineural -retrocochlear

"Rule of thumb" Quickly estimate

-double sound sources = +3 dB SPL1 + 3 dB < sum < SPL2 + 3 dB

Intensity Basic dB "Rules" to remember

-doubling of intensity: +3 dB -halving of intensity: -3 dB -factor of 10 increase in intensity: +10 dB -factor of 10 decrease in intensity: -10

Pressure: Pascals Basic dB "Rules" to know!

-doubling of pressure: +6 dB -halving of pressure: -6 dB -factor of 10 increase in pressure: +20 dB -factor of 10 decrease in pressure: -20 dB

Signal-to-noise ratio

-how intense does the tone signal (Ps) need to be for detection in the presence of noise masker with power spectrum level (N0) -N0 increases, the Ps goes up by the same amount -SNR is a key factor in tone detection in noise

temporal onset and offset cues

-when sounds begin at the same time, or nearly the same time, they appear to be coming from the same sound source -group different harmonics into a single complex tone -Attack: part of a sound during which amplitude increases (onset) -Decay: part of a sound during which amplitude decreases (offset)