Foam insert eartips offer superior sound isolation compared to regular headphones. This isolation is crucial, especially in hearing tests, where external noise can affect the accuracy of the results. By fitting snugly in the ear canal, these eartips minimise external sound interference, ensuring a more accurate hearing test outcome.

Another significant advantage is the comfort and fit. Foam insert eartips are designed to conform to the unique shape of your ear canal. This personalised fit not only increases comfort during extended use but also improves sound delivery directly into the ear, enhancing the overall audio experience.

From a hygiene perspective, foam insert eartips are a step ahead. They can be replaced easily, ensuring that each use is as clean and hygienic as the first. This feature is particularly beneficial in clinical settings where multiple patients undergo hearing assessments.

In air-conduction audiometry, three primary types of earphones are used: supra-aural, circum-aural, and insert earphones. Supra-aural earphones, such as Telephonics TDH39 and TDH49, rest on the ear and are traditional choices for audiometry. Circum-aural earphones like the Sennheiser HDA200 cover the entire ear. Both types, however, can be cumbersome and may cause ear canals to collapse, especially during bone-conduction threshold masking.

Insert earphones, such as those from The Hearing Lab Store, have gained popularity due to their disposable foam tip that directs sound straight into the ear canal. This design prevents ear canal collapse and reduces transcranial transmission of sound, thereby minimising the need for masking. However, they may not be suitable for ears with infections, obstructions, or abnormalities. In cases with earwax, these earphones could potentially push the wax further into the canal.

It's crucial for the tester to properly fit the earphones. Subjects should be instructed not to adjust them after placement. For supra- and circum-aural headphones, alignment with the ear canal entrance is essential. With insert earphones, the ear tip should be inserted so that its outer end is flush with the ear canal entrance. Incorrect placement can invalidate calibration and reduce protection from ambient noise.

Masking becomes essential in audiometric tests when the air-conduction threshold difference between the ears exceeds 40 dB with supra- or circum-aural headphones and 55 dB with insert earphones.

Cross-hearing is a phenomenon where sound intended for one ear is detected by the other, particularly in cases where there is a significant difference in hearing acuity between the ears. This issue arises due to interaural attenuation or transcranial transmission loss, which varies based on the individual and the type of earphones used.

The transcranial transmission loss with supra-aural or circum-aural earphones ranges between 40-80 dB. Insert earphones offer a higher minimum transcranial transmission loss of 55 dB, assuming correct insertion. This higher loss with insert earphones reduces the likelihood of cross-hearing.

Masking is necessary when the difference in not-masked air-conduction thresholds between the ears is 40 dB or more for supra- or circum-aural earphones and 55 dB for insert earphones. Reliance on the subject's report of which ear detects the sound is not advised, as many individuals struggle with accurately identifying the ear of perception, and sounds may not be fully lateralised to one ear.