Sound pressure level from E-drums
Image by Free-Photos from Pixabay
The greatest difference between acoustic drums and electronic drums is that you can control the sound pressure level from the electronic drums by turning the volume knob. Whereas an acoustic drum kit will produce a sound pressure level that is what it is. If you want to play rock or metal, you need to hit the drums hard, or it will not sound or feel right. Consequently, the sound pressure level will be very high. The drummer only has one option, and that is to wear proper hearing protection while drumming, or face a near certain risk of permanent hearing loss. With the E-drums on the other hand, you can choose whatever sound pressure level that you like, and your ears will be safe. Or will they?
I started playing E-drums in July 2019, which is close to two years at the time of this writing. I have practiced 15 minutes every day and I did not use hearing protection for the first 1½ years and just chose a sound level that felt comfortable. Still, I noticed that I started to have problems with Tinnitus after my practice sessions even though the subjective experience was that it felt safe. Since a couple of weeks I have started to use sound insulating drum headphones with the monitor at a low volume inside. I have noticed a significant consequential improvement in my Tinnitus. There seems to be a connection here!
Yesterday I brought a professional sound level meter to my practice session to evaluate how loud the sound pressure level from an electronic drum kit really is. The pads on the E-drum kit are “silent”. The cymbals are made from rubber and the pads have a perforated mesh skin on them, to minimize the acoustic sound. A good E-drumkit should produce as little acoustic sound as possible, because what you really want to hear are the sampled sounds from the drum module. If the acoustic sound is loud, you have to increase the volume knob to compensate. The interesting issue here is that the acoustic sounds from the pads feels quiet. I mounted the sound level meter on a boom stand, and placed the microphone as close as possible, right above my head ~15 cm above seated ear height. That means that the sound that reaches the ear drums have travelled a little bit shorter and will thus be a little louder. My measurements are thus equal to, or less than the actual sound level that the drummer is exposed to.
I turned off my PA monitor system for the drum kit and did a measurement of a playthrough of the whole song Meshuggah – Bleed, using only my closed headphones for monitoring. The measured sound pressure level thereby represents the acoustic sound from the E-drumkit and nothing else. The results were LpA,eq = 80 dB and LpA,max = 94 dB. Honestly, this is quite loud! An equivalent sound pressure level of 80 dBA is strong but should be on the safe side. The Swedish work regulations give LpA,eq,8h = 80 dB as the limit for one eight-hour workday. So we are apparently right on the edge here. The maximum levels are a different story and should be considered dangerous with long exposure times. Remember that the levels described above only relate to the acoustic sound from the pads! In a real situation, you will have a PA monitor system nearby playing the drum sounds. This PA-system will likely be a lot louder than the acoustic sounds from the pads and cymbals. And this is the real sound pressure level that the drummer is exposed to: Acoustic and Electric sound combined. I have not measured the combined (real) sound pressure level yet, but I will do it in a future session.
So how can the maximum sound pressure level be so high, and still sound so quiet? Long story short: Human hearing has a “latency” when determining how loud a sound is. That means that short impulsive sounds (gunshots, bangs or drum hits) are so short, that the ear cannot accurately detect the loudness until the sound has ended. If you are exposed to a continuous loud sound, the latency of the ear is irrelevant. The consequence is that impulsive sounds are a lot more dangerous, than continuous sounds. I might cover this topic in another blog or video, because there is a lot more to be said on this. Until then, you should head over to Wikipedia and read up on the Stapedius reflex. And you can check out this 59 second video about my measurement.