To measure sound, a sound level meter uses a detector to separate the oscillating pressure from stead (barometric) pressure. The amplitude of the pressure is then squared and averaged over a time period. The sound pressure level is then converted to decibels. In the logarithmic scale, 0 dB is the lowest sound pressure level that the healthy human ear can hear. This value is often referred to as the hearing threshold.
Sound pressure is an average of the difference in the local air pressure that goes above and below the atmospheric background pressure of 105 N/m2. The amplitude of this pressure variation can be measured directly by a sound level meter and then used to calculate the overall sound pressure level. The sound pressure meter uses a weighting filter to account for the non-linear nature of human hearing and thus converts the variation in the air pressure into an electrical signal. This signal can then be processed by a computer to convert the measurement into a decibel reading.
So in conclusion, when patrons are looking to purchase a hearing aid, we often recommend undergoing sound pressure level testing. Sound pressure level is an absolute quantity that indicates the effective pressure of a sound relative to a reference value. It is a great way to determine the type of hearing aid they need and ensure it is a good fit for their needs.