Examination of Witnesses (Questions 5060
- 5079)
5060. Do the examiners' meetings that you were
asked about involve viewing works or some other meeting?
(Mr Johnson) The structure of the examiners'
meeting is based around discussion and information provision.
However, occasionally we view excerpts of works for discussion
and that is done on monitors. A room in an external location is
appropriate for that because what we are doing is watching something
that has already been examined and we are just having a wider
discussion on a particular point raised.
5061. If you are able to meet your occasional
needs in the way described in these documents, does it make it
more or less imperative to move from 3 Soho Square?
(Mr Johnson) It makes it less imperative, if
we can meet our needs in relation to merely the number of employees,
to move from Soho Square, if our needs were met in relation to
the meeting.
5062. You said at the beginning of your cross-examination
when asked about solutions that you disputed that one of them
was a solution. "It would not allow us to discharge our statutory
functions to a satisfactory standard." Which solution were
you referring to?
(Mr Johnson) I was referring to the provision
of insulation in the viewing theatre on the basis that such insulation
would, on the advice I have received, lead to an unacceptable
reduction in the size of the screen.
5063. The second question relates to the size
of the screen. You were asked about the frame and you said, "A
cinema screen has to have a matte black frame. It does not reach
the floor. It is as big as we can accommodate." As far as
the frame is concerned and the screen, are there any changes or
differences made to the screen to accommodate viewing different
formats of film?
(Mr Johnson) Yes. Films are filmed in different
aspect ratios. Sometimes you get cinemascope which looks like
a letter box effect. Most French films are made in a much narrower
format. The black frame around the screen moves in order to accommodate
the different ratios. You need that frame in order to make the
different size screen. Otherwise, if you were showing a narrow
ratio with the screen set up in wide screen format, you would
get white at the sides and you would get the edges that are not
supposed to be seen. If you think of top and bottom, you would
sometimes get the boom mike in which is on the print but it is
not intended to appear on the screen. It is intended to be hidden
in the black masking area around the outside of the screen.
5064. You said the frame moves. How does it
move? Is there some mechanical or other process?
(Mr Johnson) It is motorised runners which
move like that, from side to side and from top to bottom.
5065. Mr Elvin asked you about the masking around
the edge. Is it practical to reduce that if you need to have this
mechanical system?
(Mr Johnson) To the best of my knowledge, we
have the masking that is necessary to perform the function.
5066. The third point was where you referred
to service offices very close where certain tasks can be carried
out. I think you have answered that.
(Mr Johnson) Yes.
(The witness withdrew)
Mr Simon Kahn, Sworn
Examined by Mr Cameron
5067. Are you Simon Kahn?
(Mr Kahn) I am.
5068. I would like you to tell the Committee
something about yourself. In short, your professional qualifications
and experience and your current position, please.
(Mr Kahn) I am a chartered engineer
with the Institute of Acoustics and the Institution of Electrical
Engineers and I have been working in the field of acoustics and
electro-acoustics for over 25 years, including working in recording
studios, broadcasting studios and theatres. I am a principal acoustic
consultant with Capita Symonds Limited, a member of the Association
of Noise Consultants, which is a firm of independent noise and
vibration consultants. My current work includes advising clients
on the suitability of premises as commercial recording studios,
the acoustic requirements for cinemas and sound insulation requirements
for commercial, public, educational and entertainment buildings.
5069. You have prepared and the Committee has
A59 and at the front of that bundle you have a series of slides.
They were going to form the basis for your evidence. Things have
moved on slightly since you prepared that and I am sure the Committee
will not thank us if we go through every slide. I am going to
ask you to help the Committee on the main areas of difference.
If we look through the slides, rather than look at the sensitivity
of BBFC activities to external noise, as the Committee have already
heard evidence on that, you have produced in these documents a
response to Mr Taylor's report. Your exhibit three is a copy of
Mr Taylor's report. You have added paragraph numbers for Mr Taylor
as he had not done that. In your exhibit two, you have provided
a written response to his report.
(Mr Kahn) That is correct.
5070. As a result of that, unless somebody is
going to tell me that I need to do so in order to get it on the
transcript, I do not need to go through your response to Mr Taylor
because you have it in writing, sir.
5071. Mr Binley: Yes, we have it, thank
you.
5072. Mr Cameron: Can we go to SK5, please,
"Standards and Criteria for BBFC examining rooms"?[15]
I would like to ask for your view as to the appropriate standard
to be applied when considering noise environment in a film review
theatre.
(Mr Kahn) The appropriate standard
to be applied, I believe, is British Standard ISO 9568 which sets
the noise levels for various types of cinemas.[16]
It is an international standard. It is almost identical to the
recommended practice by the Society for Motion Picture and Television
Engineers, the SMPTE, the lead body on film technology. The standard
sets noise levels in noise criteria which were standards originally
proposed in 1957 in America and are still used to this day for
the specification of noise in theatres. The noise criteria are
different from dBA emissions because they set a maximum sound
level in each octave band of the frequency range; whereas dBA
is for the overall frequency range. The principal difference is
that you can have any number of different sounds which will have
the same dBA rating and you can have any number of sounds which
will have the same NC rating, but you cannot predict whether one
particular sound with a dBA rating will have a particular NC rating.
The international standard is set in an NC rating. The NC rating
curves are shown in slide seven which are extended from the original
NC rating curves down to lower frequencies and up to higher frequencies.
At each vertical line there you have an octave band centre frequency
so you measure those frequencies and compare against those curves.
The highest line curve which is above the measurement you have
made is the NC rating.
5073. Mr Binley: Could we go into the
graph a little because we need to convert from the ratings we
have been accustomed to to what you are now introducing, which
is a slightly different rating, and I would like to understand
that.
5074. Mr Cameron: Would you like to do
that now, Mr Kahn? Take us slowly through it. You must remember
the Committee Members may not have seen this graph before.
(Mr Kahn) This graph was proposed in 1957 and
has been used continuously since, and particularly it is still
used for the rating of noise in cinemas. It has a series of curves
and a series of octave bands. The numbers at the bottom are the
centre frequencies of the octave band rating. You need to make
a series of measurements at each of those frequencies, plot them
on that graph. The curve which contains below it all those measurements
is the NC rating. That is the way it is done and set in the standard.
That is different from a dBA rating because in a dBA rating, if
you do all those individual measurements, you would weight them
according to their frequency and add them all up into a single
number. Once you have that single number, you do not know what
is going on in each individual frequency. Slide 14 shows the two
criteria which are set for review rooms by this international
standard, which are NC20 and NC25.[17]
NC25 is the higher one. These are the standards that we need to
compare against. On slide 16 there are two measurements of background
noise in the theatre that we are considering.[18]
The brown measurement is the measurement made by Crossrail and
the green measurement is the measurement made by ourselves. By
coincidence, both these measurements have the same dB rating but
you can see that they come at different bands and different curves
according the different frequency ratings and they have different
NC ratings.
5075. If the criteria which you are referring
to is NC20 to NC25, while we have slide 16 in front of us, on
your reading and on Mr Thornley-Taylor's reading, how does the
theatre perform at present?
(Mr Kahn) The theatre is performing just within
the specification as shown on the background noise measurements,
the L90S. Slide 15 is showing two different parts of the measurement
made by Crossrail.[19]
These measurements are taken from figure four in the Rupert Taylor
Report, which you also have. They show a number of different percentage
measurements. L90 is the level exceeded for 90 per cent of the
time. L10 is the level exceeded for ten per cent of the time.
You can see that L10 is above the NC25 so it is slightly higher
than it should be but the measurements made by Crossrail were
made with a dehumidifier running so there was some fan noise in
addition and the dehumidifier does not run when examinations are
being made. It is a bit like the projector noise you have here.
We can see at the low frequency that noise coming in and making
a difference in the NC curve, even if it might not necessarily
make a difference to the dBA curve.
5076. You were explaining that the NC20 to 25
criterion is appropriate for film review theatres. We went on
to see what conditions were like in the BBFC theatre. Can we come
back to your slide five?[20]
You have two bullet points there, the second giving the criteria
that you have referred to. What is the first bullet point?
(Mr Kahn) That is the scope of
ISO 9568 which says, "specifies measurement methods and maximum
ratings for indoor background sound pressure levels in theatres,
review rooms and dubbing rooms." This international standard
is intended for building services noise rather than external noise.
5077. The standard is intended for building
services noise. Is that noise that comes from the outside or noise
from within the building?
(Mr Kahn) That is the noise from within the
building, from the equivalent machinery that is operating within
the building, when it is in its normal function.
5078. When we are dealing with Crossrail, we
are dealing with groundborne noise. Is that from within the building
or outside the building?
(Mr Kahn) It is from outside the building.
5079. Why are we then looking at this standard?
(Mr Kahn) We are looking at this standard because,
if you look at slide eight, slide eight is appendix A3 of this
standard and it explains why the noise levels are set at particular
levels.[21]
It says, "With too much noise, detail is obscured and, ultimately,
intelligibility suffers. With too little noise, intermittent intrusive
noise may become audible and annoying; therefore it is advisable
to use reasonable background noise levels to mask intrusive noise
sources." We need to make sure that the noise is not so loud
that we miss whether a word is half said or not said when we are
doing a critical examination for the British Board of Film Classification.
The background noise levels from the building services has to
be reasonably low but it also specifies that it should not be
too low because otherwise you will be distracted by noise from
outside and intrusive noises from groundborne noise. It sets the
level of between NC20 and NC25. If we look again at slide 15,[22]
we can see that it has set the noise level between 20 and 25 in
order to mask or hide noise from intrusive noise services. You
can see that if noise from intrusive services in any of those
individual measurements, which are the triangles, dots and squares,
are above the noise level there they are quite likely to be heard
and, if they are not heard as clear sound they could still be
distracting because somebody could lose their attention and think:
"What was that noise? What was that rumble?"
15 Committee Ref: A59, Standards and Criteria for
BBFC examining rooms (WESTCC-14805-033). Back
16
Committee Ref: A59, British Standard ISO 9568-Noise Criteria
Curves (WESTCC-14805-035). Back
17
Committee Ref: A59, Standards and Criteria-Viewing Theatre (WESTTCC-14805-042). Back
18
Committee Ref: A59, Standards and Criteria-Viewing Theatre. Levels
measured by Crossrail and BBFC (WESTTCC-14805-044). Back
19
Committee Ref: A59, Standards and Criteria-Viewing Theatre. Levels
measured by Crossrail (WESTTCC-14805-043). Back
20
Committee Ref: A59, Standards and Criteria for BBFC examining
rooms (WESTTCC-14805-033). Back
21
Committee Ref: A59, Standards and Criteria-Viewing theatre (WESTTCC-14805-036). Back
22
Committee Ref: A59, Standards and Criteria-Viewing Theatre. Levels
measured by Crossrail (WESTTCC-14805-043). Back
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