Most stethoscopes have a bell and a diaphragm. The diaphragm is used to detect high-frequency breath sounds, while the bell is used for low-frequency sounds, such as blood going through vessels, Korotkoff, blood pressure sounds and some heart gallops (e.g., S3 and S4).

Low frequency noise, considered as the frequency range from about 10Hz to 200Hz, causes extreme distress to a number of people who are sensitive to its effects. The noise levels are often low, in the region of a subject’s hearing threshold, where there are large differences between individuals.

Sound level meters can be used to measure and quantify low frequency noise. Class 1 sound level meters (as defined in the standard IEC 61672-1) will provide more accurate measurements at low frequencies as they are required to meet stricter tolerances and have a wider frequency range.

Low-frequency hearing loss means difficulty hearing low-pitch sounds. People with this condition typically have a more difficult time hearing men’s voices than women’s and children’s. They may have an especially difficult time distinguishing between vowel sounds, which are lower in pitch than consonants.

Fortunately, most conductive hearing losses can be treated medically with little or no long-term effects on the hearing. Though much less common, there are other causes of low-frequency hearing losses that stem from the inner ear and the brain.

It also makes it harder to hear vowel sounds, which are spoken at a lower-pitch than consonant sounds. Unlike high-frequency hearing loss, it’s helpful to have people speak louder, as it will improve your ability to hear lower sounds (assuming you don’t wear hearing aids).