I enjoy these conversations regarding "proper sound", "accurate", etc. I live a life of "dichotomy" with these things. I design and build my own line of guitar effects and amps. You can go though all the calculations, do everything "right" and then when all is said and done listen to it. Not always is the "correct" thing the "best sounding thing" (argued forever). I have both SS and tube amps. The SS amps are wonderfully convenient and portable. However, I prefer the sound of a tube amp (for guitar mind you). Given a "clean" SS vs. a tube I prefer tubes.
I've been listening to a lot of "live" band recordings lately and have noticed something. I will say I am "guilty" of this as well. When I record if there is a "silent period" it is not uncommon to edit it for "silence"; that is select the silent part and "clean it up" setting it to "zero". In modern recording this is done all the time. But having re-listened to some "old analog stuff" there is something to be said for the "silent parts" where there is some "ambiance" during the "silence". It gives the passage "continuity". With modern stuff it almost "starts and stops", especially if the Engineer gets over zealous and trims to much into the "sound portion".
This post made me chuckle. A few years back I was in the studio recording music for a product. The "Engineer" on the board was constantly messing about with every knob on the "board". After a day of this I asked him to stop messing with things and leave everything "flat" while recording. He patently refused saying "This is what I get paid for". I just couldn't get him to understand that this was not the way to do things. I read once that Barbra Streisand would do "final mixing" WHILE THE GROOVES WERE BEING CUT in the master record. So much for RIAA, huh?
The audio world is full of snake oil salesman. The worst I ever saw was cover plates for electrical outlets in the wall - this wa said to improve the quality of the sound in the room.
At least some people in the audio world has their heads screwed on correctly -
Check Peter Aczel's website www.theaudiocritic.com and read his older magazine articles on double blind audio testing and the influence of level differences of more than 3dB.
Thank you. That is my biggest issue with the whole music industry. As they get more 'toys' to play with, they simply cannot leave well enough alone. People regularly condemn the 'sound' of Compact Disc, but if you have ever listened to a well produced CD, they are simply amazing. Unfortunately, well produced CDs always have been rare, and the situation has only gotten worse.
I once attended a course on studio recording at a well known recording studio.
I was appalled as to what was taught about "equalizing" the sound. The teacher tweaked every knob on each parametric equalizer for each sound channel for maximum "punch" to what I would call piercing. Monitoring was done at deafening sound levels. We were informed that this was standard studio recording practice.
This "equalizing" process was then repeated when it came time to make the master CD by another expert in this field.
It would appear that to earn his keep, a recording engineer is expected to adjust every single knob on his mixing board.
It's small wonder that so many recordings sound terrible when played on good audio equipment. How can one possibly judge the sound of an audio system when the the frequency and phase response of most sound sources has been so messed up?
As I recollect, the Acoustical Company (among others) was using both instantaneous and continuous signal slew testing at least as far back as the design phase of the Quad 405 (early 1970s). They also tested with realistic speaker loads (in addition to the electrostatics, which might be regarded as unreasonable).
Leach was formalising what he and the more meticulous of his colleagues had been doing for some years.
Other than maybe telling you what can and can't be ignored, I'm not clear about the relevance of the auditory system to this discussion - as it's a fixed part of the chain (albeit variable from person to person). The parts I think significant are the impact of sound level (to get subjective test conditions right), and (for design purposes only) of masking (to give an indication of criticality)
Another audible flaw where the measurements had to catch up to trained ears was from the 1970's with transient intermodulation distortion (TIM or TIMD). It wasn't unil Prof. Marshall Leach (1940-2010) mathmatically defined it in 1977, tracing it to (lack of) amplifier slew rate. As he explained it to us in his EE4026 Audio Enginering class at Geogia Tech, amplifiers that have a high slew rate can still have TIMD, those that have slow slew rates *will* have it.
Three other factors come into play in the human auditory system for normal hearing people:
1) Ear canal resonance will vary greatly in both center frequency and Q: For my "guesstimating" for hearing aid and in-ear monitors (when I'm not using a probe tube mic (real ear measurement)), I use a figure of 2kHz for men & 2700 Hz for women, with a Q of 15; but varying that figure based on otoscopic examination for external auditory meatus texture. For more on this, google "Marshall Chasin"
2) You'll experience about 5% THD from the non-linear motion of the ossicular chain as it transforms tympanic membrane vibration into launching acoustic waves into the perilymph via the oval window;
3) Non-linear neural firing based on intensity, including direct stimulation of cochlear inner hair cells by the basilar membrane above 60dB HL (hearing level).
Editor, The Hearing Blog
I pretty much agree with everything that has been written here so far...
So anything I add is intended as clarification rather than contradiction.
I think I can be certain that the things I measure are correct. On the other hand, I cannot be certain that I am measuring everything that is important. Similarly, I cannot be certain that the way I am measuring is appropriate, albeit physiological work means the situation should gradually be improving.
That was the case when crossover distortion was routinely ignored; however, the period during which accepted measurements ignored this is long gone - and audiorasts still claim that transistor amplifiers are never the equal of valve.
Known measurements that appear to be little-understood (or underused) at the present are mostly on speakers and on listeners.
Speaker issues include:
hangover, frequency-uniformity of angular distribution, and distortion (most speaker tests only measure high-level distortion - a potential mistake, particularly when organic and other so-called intelligent materials are used).
To return to "accuracy", I agree that listener tests are critical. But they need to be blind tests. The environment and performance method are also critical. For my money all tests should sporadically reference live music. The background is that the human nervous system is quite plastic, and for short-term tests people tend to prefer what they have become accustomed to. (The best counter-example was when a researcher brought a noisy change-over switch that was not connected in any way. In the absence of a difference in the sound, the difference between the "clunks" switching one way and another appeared to colour listeners' preferences.
Hanging a curtain, rolling up a rug, or turning the speakers at an angle will noticably change the perceived sound in the room. A person's listening experience is subjective - measurements are not. So? The best advice I've been given is - "listen to the system, buy what you liked". Take into account that whay you heard in the padded listening room in the shop will sound different in your tiled floor living room.
What are the engineering and design challenges in creating successful IoT devices? These devices are usually small, resource-constrained electronics designed to sense, collect, send, and/or interpret data. Some of the devices need to be smart enough to act upon data in real time, 24/7. Specifically the guests will discuss sensors, security, and lessons from IoT deployments.