Answer:
hearing threshold
Explanation:
Hearing threshold -
it refers to the level of sound , lower than that particular level , the person won't be able to listen to any sound , is referred to as hearing threshold.
In case of adults ,
0 dB is referred to as the reference level .
Hence , from the given scenario of the question ,
Placing the headphones over the ears of the child , the process of hearing threshold is done , in order to determine the lowest sound the child can hear , calling it to be the hearing threshold.
Hence , the correct answer is hearing threshold.
