Final answer:
Sound pressure levels causing discomfort begin at 85 dB for extended exposures, severe pain at about 130 dB, and immediate tissue damage at 155 dB. Sound pressure level values are higher, particularly in water or biological tissues, compared to sound intensity levels.
Step-by-step explanation:
The sound pressure level that will cause discomfort in a listener typically begins at around 85 decibels (dB) for 8-hour daily exposures without hearing protection. However, sound pressure levels beyond 130 dB can cause severe pain, and exposure to levels around 155 dB can damage tissues in seconds. It is important to differentiate between sound pressure level and sound intensity level because sound pressure levels can appear significantly higher, especially when sound travels in water, as opposed to air. For instance, ocean noise pollution from ships might register at 200 dB on the sound pressure level scale, which corresponds to a sound intensity level below 140 dB for the same sound.
When dealing with ultrasound in medical diagnostics, the sound pressure level is used, which can be substantially higher than the sound intensity level. For example, a sound pressure level of 220 decibels, in water or biological tissues, is equivalent to about 155 dB in the air, and while it is high enough to destroy tissue, it may not appear as extreme as first thought.