Lab Evaluation of Novel Hearing Aid Coupling Method

An important decision in the fitting of hearing aids is the selection of the coupling method. Examples of coupling options include universal rubber domes and custom earmolds. When selecting a coupling method, the degree of venting must be considered.

Venting refers to an opening in the coupling method to allow for the sound transmission from the tympanic membrane to the external environment. The degree of venting has a significant impact on the hearing aid user's experience. More closed (or more occluded) coupling means the vent is smaller or non-existent. Occluded fittings allow for more low-frequency amplification, which improves hearing aid performance like directionality, noise reduction and streaming sound quality. However, occluded fittings lead to complaints of the occlusion effect, in which users complain of their own voice as sounding "boomy" and can also lead to a build-up of pressure in the ear canal which users may find uncomfortable. To relieve the occlusion effect and pressure build-ups, more vented (sometimes called open) couplings can be used by allowing low-frequency sounds to leave the ear. Despite a degradation in hearing aid outcomes like directionality, noise reduction and streaming sound quality, open fits are typically preferred for speech quality and own-voice perception - at least for hearing aid users with milder losses and near-normal thresholds at low frequencies.

The fact that two coupling options are associated with two different outcomes means that hearing aid practitioners need to make an important trade-off. Either their patient will enjoy the full breadth of the hearing aid's signal processing potential (via a more occluded fit) or their patient will enjoy better own-voice perception and relief of air pressure in the ear canal(via a more open fit). A coupling method that allows for the best of both options is left to be desired.

A recent development in coupling methods has allowed us to take advantage of both open and closed fittings in a single solution. More occluded coupling allows for more low-frequency amplification which improves hearing aid performance in areas such as directionality, noise reduction, and streaming sound quality. Whereas, open coupling options reduces complaints of the occlusion effect and is preferred for speech quality and own-voice perception by hearing aid users with milder losses. This novel coupling method will function as both an open and closed fitting depending on the environment the listener is in. State 1 is dedicated to loud environments where the listener can take advantage of noise management solutions and for streaming so they can enjoy better sound quality. State 2 is dedicated to quieter environments where the listener can enjoy better physical comfort and own-voice naturality.

This novel coupling method should theoretically exploit the benefits of both open and closed coupling methods. This study is designed to see how this novel coupling method compares to traditional domes and how this coupling method performs in various listening situations.

Inclusion criteria

• Hearing aid candidate
• Meets the fitting requirements for novel and traditional coupling options
• Healthy outer ear - no visible congenital or traumatic deformity
• Symmetrical hearing loss
• No air-bone gap greater than 10 dB at 500, 1000, 2000, and 4000 Hz
• Ability to answer questions and repeat sentences
• No history of problematic tinnitus or pain/discomfort from loud sounds
• No history of active drainage from the ears in the past 90 days
• Informed consent as documented by signature.

Exclusion criteria

• Limited mobility (not able to attend scheduled visits)
• Inability to produce reliable hearing test results
• History of active drainage from the ear in the previous 90 days
• Abnormal appearance of the eardrum and ear canal
• Known psychological problems.