![]() ![]() We call this the limits of ‘psychoacoustic perception’, but generally it means there are only so many frequencies our brain can hear accurately at one moment in time – so don’t feel inadequate if you find this aspect of drum tuning difficult! It can even be hard to hear if one is higher or lower than another, because our ears get drawn to different frequencies and our brain finds it hard to interpret all the information. Unfortunately, because of the many different frequencies being excited on the drum at the same time, it can often be really hard to hear if different points are the same or not. Beating in the drumhead means that the sound is not smooth, and you don’t get the pure tone of your drums when they are hit. In acoustics we call this condition ‘beating’ which occurs when two or more close, but not exact, frequencies occur at the same time. As mentioned, if each point around the edge of the drum has a slightly different frequency, this causes a vibration clash on the drumhead which makes the sound of the drum warble or modulate. This is because, while the F0 frequency is the same regardless of where you hit the drum, it is actually possible for the F1 frequency to be different at different locations around the edge of the drum. The F1 overtone is the frequency to listen for when tuning at the lugs and clearing the drumhead. We mentioned the differences between the fundamental (centre) frequency F0 and the first overtone F1 (excited at the edge of the drum) in the tutorial on drumhead vibration. The uneven tunings at the bottom (red waveforms) have a definite modulation and acoustic ‘beating’, as the sound of different frequencies on the drumhead clash and interact. In each case, the top (green waveform ) examples show a smooth clear decay to the sound. ![]() The video here shows a few different tunings, all recorded from the edge at a lug position on a drum. If you can hear a tone that comes in and out, sounding like a ‘wow-wow-wow’ in the decay of the sound, then it is likely that the drumhead needs equalizing.īefore we start getting into the detail, let’s have a listen to the difference in sound between drumheads that are tuned evenly and those which are tuned unevenly. An uneven (or ‘uncleared’ / ‘unequalized’) drumhead can cause unwanted frequencies to interact and cancel each other out, resulting in a pulsing, warbling or beating effect on the drum sound. Accurate lug tuning is important because, when completed, it allows the drum to vibrate evenly and smoothly. We often evaluate this at each of the lug positions around the drumhead, and make adjustments with the tension rods that connect the hoop and drumhead to the lugs and the drum shell. Lug tuning is sometimes called ‘equalizing the drumhead’ or ‘clearing the drumhead’ and ensures that the tuning is even at every point around the perimeter of the drum. ![]()
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