Lecture 4- ReSound

Question 1

What is ReSound’s hearing aid fitting philosophy?

Answer 1

Model: signal is modeled to replicate various characteristics of the natural ear

Clean: unwanted noise is removed from the signal

Balance: signal is adjusted to achieve the proper balance between low and high pitches

Question 2

What is features vs. benefits?

Answer 2

Feature: something the device has (feedback cancellation, noise reduction, etc.)

Benefit: how is the feature helpful to you and/or that particular patient

Question 3

Describe ReSound’s compression system?

Answer 3

• Fitting the patient’s dynamic range

- Limited dynamic range for high frequency sounds

Question 4

What is the compression oxymoron?

Answer 4

• The higher the CR, the more gain you can give for soft sounds without over amplifying the loud sounds
• The lower the kneepoint, the more gain gain you give for soft sounds without over amplifying loud sounds

Question 5

What are the 3 different compressor types?

Answer 5

1) Filter Bank compressor
- Minimal delay, poor resolution

2) FFT (Fast-Fourier Transform)
- Requires a log of bands to get good resolution
- Time delay (10 msec for the sound to get from the microphone to the ear drum)

3) Frequency warping compressor (ReSound)
- Designed to mimic cochlear function

Question 6

What is ReSound’s approach to noise reduction?

Answer 6

Goal: to reduce the level of unwanted noise in which the desired signal is present. Take out the noise to preserve the speech

Spectral Subtraction

• Across subtraction, the noise is subtracted band by band
• If there is a positive SNR in a band, the method does not attenuate as much speech

Question 7

What is ReSound’s approach to directionality?

Answer 7

Most effective proven way to improve the SNR, thus improving speech intelligibility

Multiscope Adaptive Directionality with Autoscope
- Beam width can be manually adjusted when using adaptive directionality

Binaural directionality

1. Pinna restoration algorithm
   - preserves timing cues ear to ear
2. Predicts the head-shadow effect
3. Bilateral compression
   - Preserves interaural level difference

Question 8

What is ReSound’s feedback cancellation?

Answer 8

Out of phase feedback cancellation

1. Static feedback
   - Acoustical feedback from vent and/or slit leaks
   - Mechanical feedback from receiver vibration
2. Dynamic feedback
   - Chewing, talking, yawning

Question 9

What is entrainment?

Answer 9

Artifacts caused by feedback cancellation

Adaptation contraints

• Prevents adaptation to tonal and transient sounds
• Crucial for open fittings, when headroom is used to add gain

Question 10

What are some current features that audiologists may not be aware of?

Answer 10

• Top rated sound quality among all manufacturers in independent study
• Adjustable time constants for compression - slower time constants may benefit those with cognitive issues
• Spatial sense for improved localization and an open listening experience
• Sound shaper - frequency compression
• Ear to ear communication
• Built in tinnitus sound therapy
• Wireless connectivity and made for iPhone at all price points

Question 11

What are good questions to ask a hearing aid representative?

Answer 11

Get a good understanding if the rep knows their product.

How does your DNR work? How does it identify background noise?

What are your directional options? What is your beam width?

What is your fitting philosophy?