DL Acoustics

Review: I asked DL [redacted] to make recommendations for noise reduction in my machine shop. He quoted me $500.00 for travel and recommendations on noise reduction. After he got here, none of his testing instruments worked and he said he would have to come back a few more times and it would cost $2000.00 and did not give me any recommendations. I contacted him through email and asked for an invoice and a report. I have had no response. I feel I didnt receive anything for my money and would like a refund. I will attach an email that I sent to him with no response.Desired Settlement: Refund in full.

Business

Response:

Rebuttal to Mr. [redacted]’s complaint

Mr. [redacted] contacted me – an independent acoustical consultant – because he was cited by the city for noise violations in the rented offices of a building he purchased, and he didn’t “know what to do”. I am nationally and locally certified acoustical consultant with over 50 years of experience. Building acoustics is my specialty.

Mr. [redacted] has installed two industrial-sized milling machines in a large shop space. The milling machines are noisy. Mr. [redacted] has bolted the machines to the concrete floor without the customary vibration isolation. The offices and shop space are on opposite sides of common walls. It is no surprise to me that the offices are noisy. But evidently it was a surprise to Mr. [redacted].

What Mr. [redacted] really wanted me to do was to provide a detailed noise reduction plan without paying for a proper investigation. I repeatedly explained that a competent noise mitigation plan could not be made without first understanding the problem. I offered to take a first step in that direction.

For $500, I would visit the site for up to 2 hours to measure noise conditions in his shop and in the shop and offices that share a common wall. The initial effort might allow me to provide general ideas of what would be involved in noise mitigation. But unless the problem was a slam dunk, a 2 hour investigation would be merely the first step in sizing the problem and would be unlikely to result in a detailed noise mitigation plan.

Rebuttal to claim that none of my (sound analysis) equipment worked

In his written complaint, Mr. [redacted] wrote: “After he got here none of his instruments worked …”

That statement of Mr. [redacted] is willfully and demonstrably false. Mr. [redacted] has to know it is false because I showed him the meter and interpreted each measurement within seconds of their completion. Results were displayed on the sound analyzer’s screen. Unfortunately for Mr. [redacted], my measured noise data and the time and frequency analysis’ of that data is preserved on my analyzer as ten time and date stamped files. The files can be deleted, but cannot be changed. The ten preserved [redacted] sound files are available for inspection at my office. They prove that Mr. [redacted] is not telling the truth.

More than false, Mr. [redacted]’s statement that “none of my instruments worked” is also malicious. It is intended to sully my professional reputation by implying that I use unreliable sound analysis equipment. Because of their false and malicious nature, I intend to investigate the possibility legal redress. I hope that the Revdex.com will join with me in any action against Mr. [redacted]’s false representations because his dishonest behavior undermines the very purpose of the Revdex.com’s system for handling complaints. If scoundrels can make false representations with impunity many will do so. They must be brought to justice if this system is to work.

To prove this statement by Mr. [redacted] false I have provided documentary proof of annual inspection and calibration of my sound equipment by a qualified and independent third party. The third party is a calibration laboratory that employs equipment and procedures traceable to N. I. S. T. (National Institute for Science and Technology.) N. I. S. T. is a federal agency that replaced the National Bureau of Standards. The sound analyzer I used for this 2 hour field study is a Bruel and Kjaer Type 2270 - a high – end sound measurement and analysis instrument that is widely respected throughout the world.

This analyzer also meets all applicable requirements for sound analyzers of ANSI (American National Standards Institute), IEC (International Electrotechnical Commission) and ISO, (International Organization for Standards.

I have also provided documentary proof that the annual service costs for my analyzer exceeds $600.

I recorded ten sound files on my visit. Included with this response is a record of these ten files. One is an ambient noise measurement made when his two milling machines were silent. The other files were made with machines running. The times and dates

Mr. [redacted] had installed two industrial – size milling machines in a building clearly intended for offices and perhaps, light manufacturing. Mr. [redacted] was cited by the city for violation of its noise ordinance in the offices. He kept asking me to tell him “what to do”.

I explained repeatedly that an ethical noise control engineer could not tell him “what to do” to solve his noise problem until it was adequately investigated. A first step would be to evaluate the noise problem by measuring noise spectra on both sides of the common wall separating offices from his noisy milling machines. He didn’t want that. He only wanted me to tell him “what to do”. I repeated my explanation several times. He never did understand. He relented only when I said I wouldn’t take the job unless he would guarantee me access to both the machines and the offices to assess the problem.

Rebuttal to statement “...and he said he would have to come back a few more times and it would cost $2000”

The receiving side of the wall hosts offices where some people are disturbed by excessive noise from the milling machines. One cannot know those noise conditions without measuring noise in the shop (source side) and on the office (receiving) side of the common wall. The difference between those noise readings is an indicator of the effectiveness of the wall as a noise barrier.

The office side is where city inspectors found that A-Weighted noise levels exceeded the noise ordinance limits. I had insisted up-front that Mr. [redacted] allow me to measure noise on both sides of the wall. Despite his aceeding to this condition when he accepted my $500 proposal, in fact he didn’t allow me to measure noise on the office side. So, if I were to complete my preliminary analysis, I would need to return on another day. I had already expended 2 ½ hours at his building, which was more than I had agreed to do for $500.

Here, Mr. [redacted] makes it seem like I was playing “bait and switch” to extract as much money as I could. But that is not true. Because Mr. [redacted] did not keep his promise, I would need to come back on another day to complete my assignment. If so, I believe it reasonable that I charge for that extra time.

Again, Mr. [redacted] wanted me to tell him how much noise remediation would cost before I could complete even my preliminary inspection. I did say it would probably probably cost thousands of dollars to upgrade the two large walls, and maybe a few thousand dollars to vibration isolate the two milling machines from the concrete floor. These machines were spewing so much vibration into the concrete floor that I could feel it through my shoes. But I did not say that the noise and vibration mitigation could be done for $2000. I didn’t know then and I don’t know now.

Sample data taken with what Mr. [redacted] stated was my “non-working” sound equipment

This sample noise spectrum below (file 028) shows 1/3 octave spectra for one of Mr. [redacted]’s two milling machines. It was measured about 1 m from the closest wall. It shows that the A-weighted noise level on the source side was 77.8 dB.

The interior wall constructions were unknown. We guessed they were probably ½” single wood stud walls with (at best) rolls of R19 insulation. Such walls have poor noise insulation at low frequencies, where machinery noise can be most intense. Notice in the graph below that measured source-side noise levels are quite intense (e.g., about 84 dB in the 63 Hz band, and about 81 dB in the 31.5 Hz band.) These low frequency noises would produce annoying hum and rumble on the office side of the wall. To design cost-effective improvements to the wall it is necessary to measure noise spectrum levels on both sides.

Rebuttal to “…and he did not give me any recommendations”

Not true. I recommended that the two milling machines that were hard mounted to the concrete floor be remounted on vibration isolators, and that the resonant frequency of their spring-mass systems be tuned to 40 Hz. I recommended that walls on the source side be covered with sound absorbing fiberglass over large spacers, creating an air gap to improve low frequency transmission loss. But I hastened to add that it probably would not add enough wall attenuation to solve the problem. I made other diagnostic recommendations as well.

Rebuttal to: “I contacted him through email and asked for an invoice and a report. I have had no response.”

I don’t recall receiving an email from Mr. [redacted]. I do recall that before I left his shop, he continued repeating his mantra “tell me what to do”. But he could not understand my answers because they were not what he wanted to hear. He didn’t recognize that he caused the problem by installing noisy industrial machinery in a building designed for offices. He didn’t realize that he was preventing a solution by demanding a noise mitigation plan before doing a proper analysis.

At that time he started insulting me personally. (I held my peace.) He said I was the worst engineer he had ever encountered in his professional career. The next day he phoned me to repeat his personal insults. I did not respond in kind. But I felt that I had put in more time and effort than I was paid for. That Mr. [redacted] was scapegoating me because he lacked the capacity to understand and act rationally on the issues, and therefore was an unsuitable client. Ultimately his offensive behavior ended our relationship.

Rebuttal to: “I feel I didn’t receive anything for my money and would like a refund”

Mr. [redacted] would not feel otherwise because he could only hear what he wants to be told. And because I try to be an ethical engineer he did not hear from me what he wanted to hear. He could not recognize or respect my patient and kindly efforts to explain the rudiments of acoustics, nor my initial good will, which is now expended.

Mr. [redacted] would get no benefit from a written report. He would be unable to understand it because it would not say what he wants it to say. Mr. [redacted] cannot understand that I gave him much more of my time than he paid for. I’ve wasted my time, training, and talents on a hateful and vindictive tyrant. I wouldn’t willingly take that abuse from anyone. Not for $500 or $5000. He owes me – and the Revdex.com - contrite apologies.

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