Do you have clients in the medical profession? Did you know that clients who perform auscultation as part of their daily work often find it difficult choosing a stethoscope that works best with their hearing aids?
Auscultation is the act of using a stethoscope to listen to internal sounds of the body. Through auscultation, medical professionals can analyze heart and lung sounds for differential diagnosis.1 A question often asked is – how should their hearing aids interface with the stethoscope?
The challenge with auscultation and hearing loss is that heart and lung signals are very soft, low frequency sounds. An amplified stethoscope helps to compensate for hearing loss by amplifying bodily sounds however there is a limitation when coupled with hearing aids – the low frequency bandwidth needed for auscultation extends well below the frequency region necessary for speech understanding. For example, the frequency range for lung sounds is from 70 Hz to 4000 Hz with most signal detection falling below 2000 Hz. The frequency range for heart signals is between 20 Hz and 650 Hz.1 As an added challenge, auscultation is sometimes performed in noisy environments.
Determining a solution that best fits your clients’ needs requires you to work together. It is important for them to be aware and counseled that heart and lung sounds might not be perceived the same when listening through hearing aids. Choosing the right stethoscope is dependent on their listening needs, the severity of their hearing loss, the type of hearing aids worn and wireless accessories used.
Below are recommendations for setup configurations, as well as programming suggestions with Phonak Marvel hearing aids.
Amplified stethoscopes with headphones and hearing aids
Stethoscope earpieces are designed with an unoccluded ear canal in mind. Thus, the earpieces are competing for space that is occupied by hearing aids.1 One consideration is to use an amplified stethoscope with over-the-ear or on-ear headphones. This allows the hearing aids to remain in the ears during auscultation.
The configurations for an amplified stethoscope with headphones include:
- On-ear headphones with hearing aids that have open or large venting, allowing auscultation signals to be transmitted via direct sound. This is ideal for clients with normal or near-normal low frequency hearing.
- Over-the-ear or on-ear headphones with custom hearing aids. Create a separate manual program with more low frequency gain.
- Over-the-ear headphones with BTEs or RICs and custom earmolds to cover the hearing aid microphones. Create a separate manual program with additional low frequency gain.
Amplified stethoscopes and hearing aid streaming
It is possible to stream signals from a stethoscope to Phonak Marvel hearing aids. There are different configuration options depending on the chosen stethoscope.
- Direct Bluetooth connectivity via a Bluetooth-enabled stethoscope
- Bluetooth streaming via a Bluetooth transmitter plugged into the stethoscope
- RogerDirect™ streaming via a Roger microphone plugged into the stethoscope
Regardless of the chosen stethoscope, consider these hearing aid factors:
- The more occluded the coupling, the lower the risk of low frequency leakage. When selecting the hearing aid coupling, choose a custom earmold with minimal or no venting, or a power dome.
- Low frequency information is important for detecting heart and lung sounds. In the streaming program in Phonak Marvel hearing aids, a low frequency boost is provided by default. The amount of gain and range of frequencies affected is dependent on the acoustic vent and receiver power of the hearing aid.
- Consider how clients would like to hear their patients when performing auscultation. Within the streaming program, the attenuation of the hearing aid microphones can be adjusted according to clients’ needs.
- If the client is experiencing distortion while streaming and performing auscultation, reduce the MPO. This would be most applicable for clients with an earmold vent. The larger the vent, the greater the risk for distortion.
In addition, consider these streaming factors:
- If the client is experiencing distortion in the streamed signal, the client may need to reduce the volume on the stethoscope. Increasing the volume too much on the stethoscope may lead to clipping of the streaming signals in the hearing aids.
- If the streaming device has external microphones, such as the Roger Select, make sure they are muted while performing auscultation to reduce the surrounding ambient noise.
- The hearing aids can automatically switch into the streaming program upon detection of the Bluetooth or Roger signal. This automatic detection allows for greater ease of use when switching in and out of the streaming program.
As there are multiple amplified stethoscopes on the market and each client has unique listening needs, a partnership between the audiologist and client is crucial in determining the right solution. Clients may need to practice and learn what to listen for, as bodily sounds may be perceived differently via the hearing aids than without them. If available, it is recommended that clients demo the stethoscope to ensure it meets their needs.
1Smith, A.U. (2019). 20Q: Amplified stethoscopes for medical practitioners. AudiologyOnline, Article 25880. Retrieved from www.audiologyonline.com
To read an article related to how you can help clients who work in the field of dentistry, here is an interesting article by Chase Smith, AuD, titled, Dentists, drills and decibels: Demystifying the danger.