Bass Gear Issue 7 : Page 102
based upon certain patterns. The cerebral cortex takes this encoded data and makes sense of it. Where is all of this going? In order to detect pitch information, these hairs need to fire in a way that encodes sufficient information for the cerebral cortex to decode the correct pitch. Our cerebral cortex has logic built in that attempts to distinguish “false triggers” from real information. As such, a number of vibrations must be detected in order for pitch to be deciphered. Until the pitch is deciphered, we perceive the vibrations as noise. Some research has shown that three cycles of 100Hz tone (about 30 milliseconds of information) is required. It is possible that the number of cycles can get shorter for louder sounds. However, even for louder sounds, the membrane has to build up to equilibrium and cannot instantaneously vibrate to its full extent. So, now take a look at Fig. B . This is me playing a slap line. Notice that the signal includes a sharp attack at each note. Let’s focus on the first note. The initial attack occurs just before 600 milliseconds, and exhibits a positive peak of just under 1 V. However, that sharp attack only lasts one cycle. As we have learned, our ear cannot discern pitch from a single cycle. So, we may perceive noise at this point, or our brain may be waiting for more information before deciding whether there was in fact, a sound, or if one or more hairs simply misfired. f;c; ! %&& $%# By the time our ear gets enough cycles to interpret this as a note, our signal level has dropped dramatically. As each note is played, there is an initial burst of energy, exceeding 1.6 V positive peak at 2.8 seconds into this performance. Despite peaking at 1.6 V, the instrument cannot sustain that level for more than a cycle. Note that my positive peaks varied from under 1 V to over 1.6 V. However, the bass always settled into a range between 400 mV and 600 mV after the first cycle. As such, our ear will filter and average that peak out so that over time, the envelope of our note is what we will perceive. Am I saying that you cannot perceive those strong peaks? No. You may or may not depending upon your ears, your encoding mechanism and the ability of your cortex to decode the information fired from the hairs in your cochlea. I am suggesting however, that those peaks may not be as important as you think. [I am setting aside artifacts such as distortion that an amplifier may generate attempting to reproduce those peaks – that is the subject of another article.] Take a look at Fig. C . This is a walking blues line. Note that the initial attack is not as prominent as the case in Fig. B , where I was playing a slap line. However, our ears encode the information that we hear, which requires time/cycles to decipher. As such, we tend to perceive our bass tone based upon its average signal. My slap line may have much larger peaks than my walking bass line. However, my walking bass line has a longer envelope. Over time, our brains will tell us that the line of either Fig. B or Fig. C will sit in the mix and the listener will perceive each – over time – as being close enough in volume that we will not be reaching for the volume knob to change the level. All this, despite the fact that at certain points in time, the charts tell us that the slap line should be clearly louder, etc. So, why are we going through all of this? Simple. It is easy to see a chart and allow your eyes to tell you something that seems clearly plausible, if not down-right obvious. However, our ears function differently than our eyes. Look at the reviews, study the charts and learn what you can. But at the end of the process, pay more attention to the in-hand review. Then, go out and try the gear yourself, and pay more attention to your own in-hand review. We spend hundreds, thousands, tens of thousands, etc on gear in the pursuit of tone. But don’t forget that the single most complicated and sophisticated gear we have is our ears. However, our ears cannot be upgraded or replaced. Moreover, no matter how hard you work for awesome tone, if you damage your ears, you will not be able to appreciate it. Being a musician is more like running a marathon, not a sprint, so you owe it to yourself, in the long run, to take care of your hearing.
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