Examination of Witnesses (Questions 19520
- 19539)
19520. NC20—3 within the studios was the
operational level.
(Mr Bell) The acceptable
level of noise caused by passing trains, yes.
19521. The Promoter says "accept within
the building nothing more than NC25" and you are saying that
is 8dB greater than NC20—3.
(Mr Bell) It is, yes.
19522. Or thereabouts.
(Mr Bell) Thereabouts, yes.
19523. What are the practical ramifications
on the operation of the studio of the impact of having an intruding
sound twice as loud as the operational level of NC20—3?
(Mr Bell) There are two
separate schools of practical ramification. One is the technical
disturbance caused to the engineers. The engineers, bear in mind,
are selected for their musical ability, their artistic acuity
and their hearing capabilities. These are people for whom hearing
is their life. They are going to be able to hear the disturbing
noise and it will directly impinge on their ability to do their
job properly in terms of both disturbance and in terms of uncertainty,
in terms of whether they are hearing it in the take or whether
they are not. It will give them an unsettled feeling as they are
working on the technical work. A second and perhaps fundamentally
stronger reason is that, although that uncertainty will impinge
on the time it takes to do the work and the happiness of the engineer,
it will also impinge on the clients' happiness with the studio
and the clients feeling that the studio is up to their standards
in terms of use. I know there are many other studios in Soho because
I have built most of them, and the capability of people to walk
out of the door and go somewhere else is very, very easy. I know
that the competitive studios do not suffer from this problem because
I built them. I know that 750, Zoo (which we did not build) and
Wave are other studios that work in competition with Ivor and
Carole's studio. It is for others to judge where they sit relatively
in the league table, but they are all at the top of the premiership
of studios. They are sitting waiting for Ivor's clients to walk
out. I have every confidence that they will if tube noises are
heard in the studio. I further have every confidence that at NC25,
in the studios you will hear the tubes passing.
19524. Mr Binley: Could I ask a couple
of questions concerning the Foley standard of NC25, or are you
coming to that?
(Mr Bell) I have introduced
those standards as showing that there are a number of standards
available to which rooms can be specified. If we are looking at
those things, I have to make a judgment, as the designer of these
studios.
19525. I understand that. Does that standard
have to be applied in any part of Grand Central Station? I want
to be clear in my mind of that.
(Mr Bell) We have not designed
any of the rooms to be NC15. NC20 in the booths and NC25 in the
control rooms.
19526. You have brought it in to give us an
understanding of your wide expertise.
(Mr Bell) I am trying to
say that there are more strict standards that apply to various
rooms which we are not saying we need to apply to. Just to go
further, the BBC have long designed studios to their three curves:
type 1, type 2 and type 3 curves. These have been very stringent
curves that have required studios to be very difficult to build
and very expensive to build and limited buildings. We have made
a judgment that you do not need necessarily to meet those strict
criterion and we are not asking to meet them.
19527. Mr Binley: I wanted to dismiss
that from my mind. It is in the book and I wanted to get it out
of my mind because it is not directly relevant to the case we
are discussing. Thank you.
19528. Mr Newberry: You are saying that
you are not asking for an unreasonably high standard.
(Mr Bell) We are not asking
for an unreasonably high standard. We are claiming that it is
a very reasonable standard. Those standards are used by our competitors
Munroe Associates and Recording Architecture and ourselves as
world standards for this kind of work. In addition Dolby specify
NC25 for the control rooms. It is what we need. That is the standard
for the background noise in the room. We then must design the
isolation criterion to keep any tunnel noise out below that. The
BBC studios, type 1 and type 2, are lower, more difficult standards
to meet than what we are asking for. We are not asking for something
that is outrageously ridiculous. It is just acceptable.
19529. Going on to your next point, is there
anything you want to add to what you have said or have you covered
that?
(Mr Bell) I think we have
covered it. The emphasis here is that the noise curve is to ensure
that there is no tunnel noise, that the colouration in the room
is neutral. Below that noise must be no interjection of external
noises. They must be designed to be at a low enough level not
to burst into the room and disturb the concentration of the engineers,
the confidence of the clients or, in extreme cases, to get onto
the recordings themselves, as Ivor has pointed out.
19530. Then you have a paragraph commenting
on the noise curve specified relating to broadband noise. Could
you elaborate on that?
(Mr Bell) I think I have
covered that. It relates to all sorts of things, mechanical plant
and external noise such as traffic. There has to be no tonal content
in the background noise and in some cases the air conditioning
noise is advanced to the limit of the NC25 to cover for any other
noises in the room that may be there. The NC25 is taken as the
smooth curve to make sure that there is no colouration. As I have
said, you are listening to the sound in an uncoloured way, like
you are looking at the painting not through a piece of coloured
glass.
19531. Turning to the last point on that page,
you say: "To this end, care is taken to ensure that the isolation
of the rooms from such noises is such they are kept to a level
which is 10dB lower than the continuous background noise."
(Mr Bell) Yes. Again, I
may not have said that as clearly as I might have done. If a helicopter
lands across the road or a boat pulls up and sounds its siren
on the Thames, the sound will burst into the room. A very, very
low level of such a tone can burst into the room, even though
it is at a lower level than the background noise here because
it is tonal and you are tuned to pick these things up. We have
to make sure that these tonal and pulsed and intermittent noises
that happen outside the studio do not break into the studio. In
order to do that, we take them to be, hopefully, 10dB below that
continuous background noise. In effect, now that we have a studio
with the NC25 noise in it and the tube noise outside, we have
measured and we think that we do not need to go to 10dB but only
to 8dB below that. So 8db below NC25, which is 3dB below NC20,
is the standard that we are putting forward. If you are up at
NC25 with a pulsed intermittent and tonal sound like a railway
train going through, I am confident you will hear it.
19532. I would like to ask you about the time
you were advising Grand Central and what could have been done.
It has been suggested to Mr Taylor that, because the company was
aware of the safeguarding, you should have constructed the studio
in a way to deal with Crossrail several years in advance of this
inquiry. How do you react to that proposition?
(Mr Bell) We can only design
for the noise we know we are designing to keep out, if you follow
me. We designed to keep out the old, rattly, loud Central Line
which is not that far away, on the understanding that the new
tube line, the new Crossrail line, would be built to a higher
standard and would be at a lower level of noise ingress than the
Central Line. It was our opinion that it was impossible to design
for something which we did not know. The commercial pressures
are such that we only have to engineer the studios as far as we
can possibly go to do the things that we know about and that we
can measure about. It was of some comfort to us subsequently that
Mr Thornely-Taylor, the acoustician on Crossrail, has said that
the new Crossrail trains will be no louder than the Central Line
in the buildings along the line of the track, which means that
our assessment of designing for the current Central Line was perhaps
the right step to take. He himself has confirmed at a meeting
which I was at, hosted by UK Post, that there should be no worry
that the trains would be louder than the Central Line. We have
designed and have successfully kept out the Central Line.
19533. When was that said to you by Mr Thornely-Taylor?
(Mr Bell) In my own personal
presence, it was said at the meeting with UK Post. I am sure someone
can provide a date for that, but it was reported to me as being
said at other meetings earlier than that.
19534. I just want to be clear that you were
there when it was said.
(Mr Bell) And, indeed, I
believe Crossrail did not produce the forecast for this building
until we pressed them to do so.
19535. I would like an answer to my question.
What you just said Mr Thornely-Taylor said to you, was to you
personally, in your presence, is that right?
(Mr Bell) It was to the
meeting in general. I was a member of the meeting there.
19536. When was it? Was it this year or last
year?
(Mr Bell) Last year in July.
19537. You say as a result of your initial researches
as to how you should design the studio and how you did design
the studio, in the light of what Mr Thornley Taylor said to you
in October of last year bears out your design criterion?
(Mr Bell) Yes, it does.
19538. Thank you very much. Can we go over the
page to the next page, and I think you have covered this but I
would like your input on this point relating to the tonal nature
of sound in the context of railways. What is the particular area
which one has to be concerned with where you are dealing with
trucks on rail or trains on rail? What is it that is exhibited
which causes you concern?
(Mr Bell) The issue there
is it is predominately low frequency noise which is difficult
to deal with. It is also tonal and bi-tonal. If you look at the
curve on the graph of such a noise, it exhibits a spike. This
is one of Crossrail's drawings. There are spikes raised in that
which represent themselves as tonal content and by that it means
the noise is not a broadband noise, it has got a pitch to it,
it has got a tonal content. That tonal content means that is more
disturbing to the people who are trying to concentrate on something
else and less easy to mask the broadband noise. It is the tonal,
low frequency and pulse nature of the railway which causes the
problem.
19539. Why is a tonal quality of sound less
easy to mask?
(Mr Bell) Because you are
trying to hide a specific tonal, I am struggling with words to
describe how to say this but, you are trying to hide something
which has got a pitch and it is identifiable and it starts and
stops because the train arrives and goes away underneath a smooth
noise tunnel.
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