How loud is loud, how to measure it? Is THX calibration bad for your health?

[abdo123]

I am sure they are lazy in this case but they do run the normalization on whatever content they used.
BTW. are you able to hear if a content is likely mixed for 79 or 85? What are indicators to listen for?

Not by ear, but analysis, I realized that most blu-rays limit the LFE to around -15dBfs. The BEQ catalogue shows the maximal signal for the low-end frequencies for many uhd and blu-ray discs.
Thus, is it likely that in these cases, someone mastered everything 10 dB lower than for cinema? Or is it common in a cinema mix to stay below -10dB in the LFE?

The LFE is always boosted by 10 dB during decoding.

 

[audio2920]

are you able to hear if a content is likely mixed for 79 or 85? What are indicators to listen for?

Hmm, so, I fear this answer isn't going to be helpful to you... but in a calibrated 85dB room, for sure I could. If someone gave me a 5.1 WAV which had been gain adjusted completely randomly and said, "this was mixed at 79 or 85, which was it?" I'd put a fader on it and push it up until the dialogue sounded right to me. If at this point I still had about 6dB of headroom in the monitoring, I.e. peaks were never higher than -6dBfs or around 99dBC per channel, then likely it's a 79dB mix.

It's unlikely I'd be comfortably able to push the fader up another 6dB without the dialogue really starting to hurt in places.

If on the other hand I set the dialogue so I'm comfortable and I end up with clipping (or getting very close to it) on the loudest thing in the film e.g. gunshots then it was mixed at 85.

But, the problem is, I'm not really sure how to describe what that dialogue level is!! It's not something I can put a number on because it's totally dependent on the dialogue itself.

Telling the difference between 79 and 82, or 82 and 85 might be a bit more difficult because if my "comfortable" is a dB or two lower than the mixer's, or vica versa, or they mixed in a less aggressive sounding room than I'm in (etc.etc.) then it might get in to the realm of uncertainty without some other knowledge (like, who mixed it, where they mixed it, who directed it etc.

Not by ear, but analysis, I realized that most blu-rays limit the LFE to around -15dBfs.

That's curious. I've never done that in the mix. Obviously there's an extra 10dB of gain to be applied to it, but that's to get 10dB louder than the other channels, not restore the balance. Maybe @Soundmixer would know more about the encoding etc as to whether -15 has any significance. Seems a bit random to me.

In cinema though, no I wouldn't say it would be common to stay below -10 throughout an entire film; although I've definitely done "dialogue films" where that could be true.

 

[Neuro]

We haven’t seen any frequency or level on any research so far. Your reference does not answer the issue either: does low frequencies are safer than high frequencies. So far you are only assuming. Will you risk your ears with wishful thinking?

Subsonic sound and some physiological consequences.

(Burdick et al., 1978) indicated
that there may be some permanent threshold shift (PTS) for long term high
level exposure. In one experiment, chinchilla were exposed for three days to
octave band noise at, 100dB, 110dB and 120dB centred on 63Hz. The highest
level led to PTS of up to 40dB at 2kHz in the chinchilla. When human subjects
were exposed to the same low frequency noise at 110dB and 120dB for four
hours, a TTS of about 15dB resulted, extending from low frequencies up to
2kHz. The frequency used by Burdick et al is higher than in the other
experiments and might be expected to have a greater effect. There is an
indication that long-term exposure to very high levels may cause permanent
hearing loss.
The major results were (1) high‐frequency hearing loss to a low‐frequency noise and (2) that noise bands matched within 1 dBA were not equally hazardous as dictated by damage‐risk criteria. The 63‐Hz noise band produced nearly twice as much PTS as the 1000‐Hz noise band.

Cookie Absent

Persson and Rylander (1988) surveyed all the 284 local authorities in
Sweden with respect to complaints from heat pumps, heavy traffic and fan and
ventilation installations.
Exposure to 6 and 16 Hz levels at 10 dB
above the auditory threshold have been associated with a reduction in
wakefulness (Landström and Byström, 1984). It has also been possible to
confirm that the reduction on wakefulness is based on hearing perception since
deaf subjects have an absence of weariness (Landström, 1987).
hus although exposure to infrasound
at the levels normally experienced by man does not tend to produce dramatic
health effects, exposure above the hearing perception level will produce
symptoms including weariness, annoyance, and unease. This may precipitate
safety concerns in some environmental and many work situations (Landström
and Pelmear, 1993)
The primary effect of infrasound in humans appears to be annoyance.
(Andresen and Młller, 1984; Broner, 1978a; Młller, 1984)
Beginning at 127 to 133dB, pressure sensation is experienced in the middle ear (Broner 1978a). Regarding potential hearing damage Johnson (Johnson, 1982) concluded that short periods of continuous exposure to infrasound below 150dB are safe and that continuous
exposures up to 24 hours are safe if the levels are below 118dB.
Lidstrom (Lidstrom, 1978) found that long term exposure of active aircraft pilots to infrasound of 14 or 16Hz at 125dB
produced the same changes. Additional findings in the pilots were decreased
alertness, faster decrease in the electrical resistance of the skin compared to
unexposed individuals, and alteration of hearing threshold and time perception.
The ability of infrasound (5 and 16Hz at 95dB for five minutes) to alter body sway responses suggested effects on inner ear function and balance (Tagikawa et al., 1988).
However, Evans (Evans and Tempest, 1972) examining the effect of infrasonic environments on human behaviour found that 30% of normal subjects exposed to tones of 2 – 10Hz through earphones at SPLs of 120 – 150Hz had nystagmus within 60 seconds of exposure to the 120dB signal, with 7Hz being most effective in causing it. Higher intensities
resulted in faster onset of nystagmus, but there were no complaints of
discomfort from any of the subjects at any SPL.
Subsequently, Johnson (Johnson, 1975), who investigated nystagmus in many experiments under different conditions with aural infrasound stimulations from 142 to 155dB had
negative results. For example, an investigator stood on one leg with his eyes
closed, listening aurally to 165dB at 7Hz and 172dB at 1 to 8Hz (frequency
sweep) without effect
Alekseev (Alekseev et al., 1985) exposed rats and guinea pigs (5 test animals,
2 controls per group) to infrasound (4 to 16Hz) at 90 to 145dB for 3 h/day for
45 days; and tissues were collected on days 5, 10, 15, 25, and 45 for
pathomorphological examination. A single exposure to 4 to 10 Hz at 120 to
125dB led to short-term arterial constriction and capillary dilatation in the
myocardium. Prolonged exposure led to nuclear deformation, mitochondrial
damage and other pathologies. Effects were most marked after 10 to 15Hz
exposures at 135 to 145dB. Regenerative changes were observed within 40
days after exposure.
Gordeladze (Gordeladze et al., 1986) exposed rats and guinea pigs (10
animals per group) to 8Hz at 120dB for 3 h/day for 1, 5, 10, 15, 25, or 40 days.
Concentrations of oxidation-reduction enzymes were measured in the
myocardium. Pathological changes in myocardial cells, disturbances of the
microcirculation, and mitochondrial destruction in endothelial cells of the
capillaries increased in severity with increasing length of exposure. Ischemic
foci formed in the myocardium. However, changes were reversible after
exposure ceased.
Male rats (10 /group) exposed to infrasound (8Hz) at 100 and 140dB for 3
h/day for 5, 10, 15, or 25 days showed constriction of all parts of the
conjunctival vascularture within 5 days (Svidovyi and Kuklina, 1985). Swelling
of the cytoplasm and the nuclei of the endotheliocytes accompanied the
decrease in the lumen of the capillaries. The capillaries, pre-capillaries, and
arterioles became crimped. Morphological changes were reported in the
vessels after exposure for 10, 15, and 25 days. After 25 days, increased
permeability of the blood vessels led to swelling of tissues and surrounding
capillaries and to peri-vascular leukocyte infiltration. Significant aggregates of
formed elements of the blood were observed in the large vessels.
Morphological and histochemical changes were studied in the hepatocytes of
rats and guinea pigs exposed to infrasound (2, 4, 8, or 16Hz) at 90, 100, 110,
120, 130 or 140dB for 3 h/day for 5 to 40 days (Nekhoroshev and Glinchikov,
1992a). Hepatocytes showed increased functional activity, but exposures for
25 and 40 days induced irreversible changes. Changes were more pronounced
at 8 and 16Hz than at 2 and 4Hz. Exposures impaired cell organoids and
nuclear chromatin. Single exposures did not induce any changes in the
hepatocytes and small blood vessel
(Shvaiko et al., 1984) found that rats exposed to 8Hz at 90, 115, or 135dB
exhibited statistically significant changes in copper, molybdenum, iron, and/or
manganese concentrations in liver, spleen, brain, skeletal muscle, and/or
femur compared to concentrations in the tissues of controls. Practically all
tissues showed significant changes in all the elements for exposures at 135dB.
Changes included elevations and depressions in concentrations. The trends
were consistent with increasing sound pressure except for some tissue copper
values.
Harding GW, Bohne BA.
The relation between total noise-exposure energy, recovery time, or rest during the exposure and amount of hair-cell loss was examined in 416 chinchillas. The exposures were octave bands of noise (OBN) with a center frequency of either 4 kHz at 47-108 dB sound pressure level (SPL) for 0.5 h to 36 d, or 0.5 kHz at 65-128 dB SPL for 3.5 h to 432 d. Recovery times varied from 0 to 365 d … (4) except for the highest exposure levels, the majority of outer hair cell loss from the 4 kHz OBN occurred after the exposure had terminated, while that from the 0.5 kHz OBN occurred during the exposure; and (5) a majority of the inner hair cell loss from both OBNs occurred post-exposure.
(Nishimura et al., 1987) suggested from experiments on animals that
infrasound influences the rat’s pituitary adreno-cortical system as a stressor,
and that the effects begin at sound pressure levels between 100 and 120 dB at
16Hz. The concentration of hormones shows a slight increase with exposure to
infrasound. In the task performance a reduction was seen in the rate of
working. It seems probable that concentration was impaired by infrasound
exposure.
(Nekhoroshev and Glinchikov, 1992b) exposed rats and guinea pigs (3 per sex
per dose level) to 8Hz at 120 and 140dB for 3 hours or 3 h/day for 5, 10, 15,
25, or 40 days and they showed changes in the heart, neurons, and the
auditory cortex increasing in severity with increasing length of exposure. The
presence of hemorrhagic changes are attributed mostly to the mechanical
action rather than to the acoustic action of infrasound. They suggested that the
changes in the brain may be more important than in the ears
Histopathological and histomorphological changes were determined in the
lungs of male albino mice exposed to infrasound (2, 4, 8, or 16Hz) at 90 to
120dB for 3 h/day for up to 40 days (Svidovyi and Glinchikov, 1987). After
prolonged exposure to 8 Hz at 120 dB sectioned lungs revealed filling of acini
with erythrocytes and thickening of inter-alveolar septa; after prolonged
exposure to 8 and 16Hz at 140dB sectioned lungs revealed ruptured blood
vessel walls, partially destroyed acini, and induced hypertrophy of type-II cells.

 

[MKreroo]

Exactly, you can use an SPL meter or an app, which is often not too far off.
The differences come from what you expect the outcome to be. As mentioned earlier, most standards opt for your hearing to be sufficient for a conversation after 40 years at this exposure but your hearing might still be damaged. Look a few posts earlier with the links to the corresponding studies.
70dBa is probably another step towards maintaining a healthier hearing.

That's good to know, I did a quick measure with the app and set the gain such that my noise floor would be around 45 (just as a conservative measure), and turns out I listen at around high 60 dB (probably lower in reality??) so I guess I'm somwhat safe

I would buy a dedicated calibrated SPL meter. They are not that expensive. You don't know if you can trust any app.

Indeed that will be better, but I think it's somewhat established here that the app is sufficient for average user (albeit the calibration setting is another thing to worry about), I set it such that the noise floor measured will be higher than usual, just to get an idea of where my listening level is. If it's close to the recommendation then I should be safe given the extra mic gain applied.

 

[Soundmixer]

Not by ear, but analysis, I realized that most blu-rays limit the LFE to around -15dBfs.

I have never heard of this.

 

[sarumbear]

I have never heard of this.

Could it be due to the talk about LFE being amplified by 15dB on amplifiers and they want to avoid reaching 0dBFS?

 

[audio2920]

@Neuro regardless of very high level infransonics, the interesting take away for me on your post is that hearing loss can occur later in life from earlier exposure. I've tended to think it was as simple as hearing damage occurs earlier in life, then aging happens bringing with it more loss, and the hearing loss is just the cumulative effect of both of those things.

But some of that research, or rather some of referenced research, concludes that damage can hide as it has changed other parts of the ear (rather than simply inner and outer hair) which then results in additional loss later. So, you have your ears damaged through SPL, they go back to normal less any permanent threshold shift, but years later, the threshold shift reappears outside of the damaged frequencies through mechanisms other than "hair loss". Fascinating, if not scary, stuff.

 

[sarumbear]

@Neuro regardless of very high level infransonics, the interesting take away for me on your post is that hearing loss can occur later in life from earlier exposure. I've tended to think it was as simple as hearing damage occurs earlier in life, then aging happens bringing with it more loss, and the hearing loss is just the cumulative effect of both of those things.

But some of that research, or rather some of referenced research, concludes that damage can hide as it has changed other parts of the ear (rather than simply inner and outer hair) which then results in additional loss later. So, you have your ears damaged through SPL, they go back to normal less any permanent threshold shift, but years later, the threshold shift reappears outside of the damaged frequencies through mechanisms other than "hair loss". Fascinating, if not scary, stuff.

My job here is done

 

[Thomas_A]

@Neuro regardless of very high level infransonics, the interesting take away for me on your post is that hearing loss can occur later in life from earlier exposure. I've tended to think it was as simple as hearing damage occurs earlier in life, then aging happens bringing with it more loss, and the hearing loss is just the cumulative effect of both of those things.

But some of that research, or rather some of referenced research, concludes that damage can hide as it has changed other parts of the ear (rather than simply inner and outer hair) which then results in additional loss later. So, you have your ears damaged through SPL, they go back to normal less any permanent threshold shift, but years later, the threshold shift reappears outside of the damaged frequencies through mechanisms other than "hair loss". Fascinating, if not scary, stuff.

There is however, no indications in that research that occasional exposure to average 85 dBSPL with dynamic music material has any impact on hearing loss.

 

[Soundmixer]

Could it be due to the talk about LFE being amplified by 15dB on amplifiers and they want to avoid reaching 0dBFS?

As a person doing the mastering and encoding, how am I to know which amps do that and which don't? This would be an encoding/decoding issue, not an amp issue. There is no reason to do this. It would be a moving target that can't be effectively aimed at.

 

[abdo123]

As a person doing the mastering and encoding, how am I to know which amps do that and which don't? This would be an encoding/decoding issue, not an amp issue. There is no reason to do this. It would be a moving target that can't be effectively aimed at.

All LFE content is boosted by 10 dB in the decoding step, it might be the ONLY industry standard that is actually respected by everyone.

 

[Soundmixer]

All LFE content is boosted by 10 dB in the decoding step, it might be the ONLY industry standard that is actually respected by everyone.

They have no choice. The decoding software is fixed so the manufacturers nor the consumer can change it.

 

[abdo123]

They have no choice. The decoding software is fixed so the manufacturers nor the consumer can change it.

my point was that this is what @sarumbear was referring to.

 

[EEE272]

@audio2920 @Soundmixer
I have to apologize for giving some false information about the limit of the LFE to -15dB on many blurays. It seems BEQ, which I referred to, uses a scale of WCS not the LFE - I was unaware of this and it was not indicated in the graph.

WCS means worst case signal, which integrates the mains' low-frequencies into the LFE. Depending on whether it is a 5.1 or a 7.1 mix, they choose a different SPL reference. For 7.1, they set the WCS to 125dBC.
Thus, when they show -15dBFS, it should mean 110dB SPL.
So the LFE is probably indeed at about 5 dBFS and then the contribution of the mains comes on top.

These loudness topics are really complicated...
Again, sorry for my mistake.

 

[audio2920]

I have to apologize for giving some false information about the limit of the LFE to -15dB on many blurays

No need to apologise! Especially to me, I only said it seems random Obviously things aren't often truly "random" so well done for figuring it out and posting back!

I've not been on ASR long but I don't think anyone should worry about posting flawed observations. It's an internet forum, which by definition is for open discussion, not a 5 year research project you're submitting for peer review. (Although, it can feel like it with some people... like you've offended them to their core by being human and making an error. But that's up to them.)

 

[Soundmixer]

I have to apologize for giving some false information about the limit of the LFE to -15dB on many blurays. It seems BEQ, which I referred to, uses a scale of WCS not the LFE - I was unaware of this and it was not indicated in the graph.

As Audio2920 stated, no need to apologize. I knew BEQ is where you got that number from! Their measurement scale seems to peak at -15, so it is easy to think that was the maximum level encoded.

 

[MKreroo]

I would buy a dedicated calibrated SPL meter. They are not that expensive. You don't know if you can trust any app.

After a bit more digging, I realised that since my amp (Qudelix) tells the voltage output, I can do a rough calculation of what the SPL level I listen to, using hd-650's sensitivity @ 1kHz, or do a power calculation too.
I'm not sure though, that if this calculated dB SPL using the 1kHz sensitivity will be the same for all frequency, though I suppose it is since SPL isn't freq. dependant (?), or maybe the using the efficiency instead can avoid the problem....

Assuming I manage to get the estimated SPL level, how should I go about finding whether if this level is safe or not? I'm assuming I need to see which phon line I'm on, and go from there?

 

[Chromatischism]

SPL isn't freq. dependant (?)

It sure is. What speakers do you have again? Are you talking about the Sennheisers? If that's the case they are pretty neutral.

Sennheiser HD650 – In-Ear Fidelity

2020 Sample (w/ worn pads) Pre-2020 Sample 2 (w/ worn-ish pads) Pre-2020 Sample 1 (w/ worn pads)

crinacle.com

 

[MKreroo]

It sure is. What speakers do you have again? Are you talking about the Sennheisers? If that's the case they are pretty neutral.

Sennheiser HD650 – In-Ear Fidelity

2020 Sample (w/ worn pads) Pre-2020 Sample 2 (w/ worn-ish pads) Pre-2020 Sample 1 (w/ worn pads)

crinacle.com

indeed it is about the Senn's.
It was mainly that I came across this from oratory that I had the idea about calculating volume based on power, and power based on the power budget chart given by Qudelix.

On another note, I suppose they won't be neutral after EQ to Harman, so how should I go about estimating the loudness based on that.

 

[Andysu]

Question is for most of the posters here is and the OP is. Have you actually been to a THX cinema and if so name the site and movie that you saw.
I don't have to answer mine. I been to the CIC Empire Leicester Square, the CIC High Wycombe and the Warner village west end.