1. Sound recording tools

A measuring microphone at a person's location does not give an accurate picture of the sound that will reach that listener's ears. This is because the sound field is modified by the presence of the human body in a way that depends on the frequency and direction of incidence of the sound. The head is an effective natural obstacle at frequencies above 1,500 Hz, and reflections occur on the listener's shoulders and, at higher frequencies, in the pinna. These changes vary according to the incidence of the sound. Others, however, are independent of incidence: these are the resonances of the auditory canal, which amplify frequencies around 2,500 Hz; this frequency corresponds to the quarter-wave mode of a cylindrical tube open at one end (the pinna) and closed at the other (the eardrum), by which we can, to a first approximation, represent the auditory canal.

These two...