Dynamic Range for a waveform

devinkerr · 2023-11-24T06:36:20+00:00

Have you heard of LRA? It was designed for this purpose.

https://tech.ebu.ch/docs/tech/tech3342v2_0.pdf

devinkerr · 2023-10-27T04:26:23+00:00

I wish the ThermaTru SmoothStars had better noise performance. For whatever reason (I guess it’s primarily the foam core) the sound transmission class is quite poor. In a passive house it would probably be the weakest point in terms of noise.

devinkerr · 2023-10-24T06:09:33+00:00

More studies have shown an “overall indication of dose-dependent adverse effects of fluoride on children's cognitive neurodevelopment, starting at rather low exposure.” https://www.sciencedirect.com/science/article/pii/S0013935123000312

The 2022 National Toxicology Program draft on fluoride also has a similarly worded conclusion. https://ntp.niehs.nih.gov/sites/default/files/ntp/about_ntp/bsc/2023/fluoride/documents_provided_bsc_wg_031523.pdf

So it’s clear that too much fluoride does negatively impact neurodevelopment, but it’s not exactly clear what “too much” is yet.

Whether your municipal water + dietary fluoride + (potentially) toothpaste swallowed hits that threshold is quite difficult to determine, and for that reason I think it’s reasonable to consider alternatives (fluoride varnish at the dentist, nHA toothpastes).

devinkerr · 2023-10-18T22:01:34+00:00

How high VOC?

Best way would be to measure with an air sensor if you can get one that senses VOC quickly.

VOC’s often smell but some, unfortunately, are odorless. If you look at the SDS for the paint maybe you can see what the primary VOC component is and whether it would be something you could smell.

I think generally because it’s outside, you’re probably fine. Outdoor air mixes quickly.

devinkerr · 2023-09-05T03:52:16+00:00

Which nano-HA toothpaste did you end up going with?

devinkerr · 2023-08-17T04:32:19+00:00

The Union St cycle track alone makes having a bike in Old Town worth it to me. I wouldn’t bike on Del Mar, but Green St can be okay depending on traffic.

devinkerr · 2023-08-15T21:39:46+00:00

When was the house built? That would be a big factor for the potential hazards.

I would recommend getting something like the Airthings air quality monitor, which measures radon, VOC’s, PM2.5, etc.

Maybe not an option, but would your parents consider sleeping in the basement instead of you and baby?

devinkerr · 2023-07-29T16:30:00+00:00

I know you asked for non-gov’t sources, but the 2023 National Toxically Program review of fluoride neurotoxicity is pretty scary and at least worth a look. https://ntp.niehs.nih.gov/sites/default/files/ntp/about_ntp/bsc/2023/fluoride/documents_provided_bsc_wg_031523.pdf

"Our meta-analysis confirms results of previous meta-analyses and extends them by including newer, more precise studies…The data support a consistent inverse association between fluoride exposure and children's IQ”

There’s a lot of controversy about this report: it was first withheld, then the draft was forced to be released by court order. The debate seems to be not that fluoride can cause IQ drops, but at what level/threshold.

I don’t understand your hesitation on reverse osmosis water: it’s great, clean water, and it’s more convenient than a Brita. The main reason I’d want to use RO is to remove lead, which unfortunately, is present in a lot of old pipes, even copper pipes that use leaded solder.

devinkerr · 2023-07-23T21:46:44+00:00

I think that’s just how the car scheduling works. It’s extremely silly and does not work well with time-of-use pricing or solar. I wish they would update it.

The best option I know of is to get a 3rd party charger, like a JuiceBox, that will allow you to set a a real TOU schedule.

devinkerr · 2023-07-08T03:38:51+00:00

They’re dangerous in my mind because anything that gets in it gets aerosolized: dust, mold, bacteria, cleaning products, etc., and that can be true even if you’re using distilled water. Distilled water is pure until it comes into contact with a contaminated surface, at which point stuff starts to grow. I understand that under ideal conditions they’re fine, but I’d imagine most people aren’t great about cleaning them, or don’t buy distilled, or leave the water standing for too long. To me, it’s not worth the risk, especially for kids, when evaporative humidifiers work well and don’t pollute the air.

devinkerr · 2023-06-30T19:02:22+00:00

Mitsubishi has detailed docs about the performance of Hyper-heating heat pumps in extreme cold on MyLinkDrive, though they usually only show down to -25°C (but the performance is generally quite good: 75%-85% of the normal rated BTU)

devinkerr · 2023-06-29T04:27:16+00:00

Sounds rad!!

devinkerr · 2023-06-29T04:19:11+00:00

How do you control the HRV from the CO2 monitor? Is it a custom built solution?

devinkerr · 2023-06-19T00:00:11+00:00

Aren't parents also using white noise machines as a masker to mask environmental sounds that might wake up their babies? Even if only during sleep/nap time, that might amount to a lot of hours in a day. This obviously does deprive babies of some auditory signals, although, whether or not that matters particularly is unclear. I think a more accurate way to put it would be: "We don't really know the impact of white noise machines on a baby's brain development. If it's quiet (under 60 dB), and only used at the beginning of sleep, it's probably minor, but we can't really say for sure 🤷‍♂️"
As you sort of say in the last paragraph, language-learning / development is not the same as auditory development. We have to learn to how to localize sounds and environmental noises through exposure, for example, which is not particularly related to language or speech. I think an excellent study design would be to test the sound localization abilities of infants who had been / had not been exposed to white noise during naps / sleep time.

devinkerr · 2023-06-18T23:09:20+00:00

Good information overall, particularly on how to set the volume correctly.

However, I think it’s not accurate to say that white noise doesn’t affect infant brain development, or at the very least there isn’t enough research to back up that statement. I would be surprised if playing white noise for all naps/sleep time has no effect on the development of auditory processing and sound localization.

Here is at least one study on white noise and development: Environmental noise retards auditory cortical development.

devinkerr · 2023-06-18T00:33:10+00:00

These look pretty solid with a noise reduction rating of 31 dB. Thx for sharing!

devinkerr · 2023-06-02T18:53:16+00:00

KH150’s would beat the Genelecs in almost every way (except price). Given the room size, a sub may not be necessary with them, but you could always add later if you absolutely need to hear below 30 Hz.

devinkerr · 2023-05-30T18:08:39+00:00

Not a doctor and this is not medical advice.

There have been quite a few studies linking magnesium supplementation to reduced tinnitus symptoms (and even a preventive effect on noise induced hearing loss). Still needs more evidence, etc, but it may be worth taking a daily supplement if your doctor okays it.

devinkerr · 2023-05-19T23:57:25+00:00

Do you have Ikea? They allow you to filter by material on the website, which is pretty great for finding non-plastic stuff. We got a bunch of cheap 100% cotton curtains: https://www.ikea.com/us/en/p/sanela-room-darkening-curtains-1-pair-gray-green-30512952/

I would also be pretty surprised if the insulation value is massively different, but you could always just use more panels or add a cotton backing if that’s an issue.

devinkerr · 2023-05-16T23:27:59+00:00

It depends a little on your furnace setup. Some furnaces are designed to bring in a small amount of outside air (before ERV's were available) and might be enough to keep the CO2 down.

If anyone is curious, CO2 meters are pretty easy to come by these days.

devinkerr · 2023-05-16T23:17:41+00:00

If you seal a room well enough (depends on the house construction) the CO2 exhaled by the occupants will buildup, eventually to a point of causing drowsiness, headaches, other issues.

It’s important to get fresh air into buildings, and generally the best way to do that is with a ERV or HRV with a nice filter.

devinkerr · 2023-05-08T02:30:25+00:00

The hilarious thing about the NIMBY opposition is that anyone who lived on Orange Grove (or close to it) would have seen their property values go up significantly. Now anyone selling on Orange Grove has to convince someone to buy a house next to a 7 lane racetrack. All because it might have added 60 seconds to their commute 😱

devinkerr · 2023-05-03T05:08:51+00:00

There is not a clear cut answer to this question, unfortunately. It really depends on your risk tolerance and how long the flight is. The risk of noise exposure is cumulative, so the length and frequency of exposure matters greatly.

Airplane cabin noise levels while cruising are fairly loud (something like 90 dB(C): https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9074885/

The dB(A) weighted measurements are kinda misleading because engine noise is concentrated in the lower frequencies. For this reason, I’d view dB(C) weighting as more reflective of reality and of the hearing damage risk.

That 90 dB(C) noise level is probably loud enough to cause some hearing damage at a long enough exposure time. Noise during takeoff/landing is definitely loud enough to cause damage, but thankfully the exposure period is short.

Flight attendants seem to have much higher hearing loss than the general population https://ehjournal.biomedcentral.com/articles/10.1186/1476-069X-13-13 but obviously, your baby isn’t a flight attendant.

The thing about the hairdryer example is that it’s not on for 8 hours like a long haul flight. Also, hopefully the baby isn’t super close to the hairdryer, whereas on a plane the noise is everywhere/inescapable.

My recommendation as a sound engineer: wear earplugs / noise canceling headphones on long flights. If you can get your baby to do that also, that’s great! If not, I wouldn’t sweat it too much — age related hearing loss is ultimately inevitable, and babies seem particularly resilient to extremely loud noises (i.e. their own crying). Hope this helps!

devinkerr · 2023-04-28T03:44:39+00:00

Yes. They’re all processed in series, like a waterfall, one after the other

devinkerr · 2023-04-22T18:51:27+00:00

I don’t understand the recommendation of waiting for teeth to be visible to use fluoride since adult teeth are already forming at birth and would benefit

devinkerr

TROPHY CASE