Which signal measurement standard is represented by 45 dB HL or 65 dB SPL?

The measurement standard expressed as 45 dB HL (Hearing Level) or 65 dB SPL (Sound Pressure Level) pertains to the Normal Hearing Threshold. The Normal Hearing Threshold typically refers to the lowest sound level that can be detected by an average person with normal hearing. In audiometric assessments, thresholds are often measured in decibels HL, which are specifically calibrated to reflect the average hearing ability of the normal population for various frequencies.

The significance of 45 dB HL aligns with the range of auditory perception that is considered typical for individuals without hearing impairment, where they can perceive sounds reliably. The reference to 65 dB SPL also indicates a sound level that is usually within the range understood as comfortably heard without discomfort for someone with normal hearing. Thus, both measurements collectively illustrate the baseline thresholds that define normal auditory function in a clinical context.