With the difficulties of the auditoria ceilings all but solved, Utzon might have thought things were about to improve. However, the pressures continued to build up.
On 24 February 1966, there was a meeting between Stan Haviland and representatives of the ABC to discuss various fairly mundane matters, such as lighting, where to put TV vans during broadcasts and wiring. At the meeting, Warwick Mehaffey, ABC's acoustics engineer, dropped a bombshell. He announced that the Major Hall was quite unsuitable for concerts by the Sydney Symphony Orchestra because it did not have enough seats to make it financially viable, there was not enough volume to give the required reverberation time, the rehearsal room was not big enough, there was inadequate provision for television and recording cables and, to cap it all, the problem of harbour noises penetrating the auditoria seemed unsolved.
Mehaffey had plenty of experience in building concert halls; he had designed the acoustics for the ABC studios in Perth and, in 1966, was working on the acoustics for the Perth Concert Hall and the Adelaide Festival Theatre. He was greatly influenced by the work of the BBC Research Department in England, one of the leading centres of acoustical research at the time and which took a somewhat traditional view of the design of space for music. Tom Somerville, head of the department, wrote to Mehaffey after Utzon's resignation: 'I am very interested in your remarks about the Sydney Opera House. Many years ago I was asked by one of the entrants in the competition if I would be prepared to help him with the acoustics, but when he explained the specification, which was that it should be suitable for opera of all types and also symphonic music, I refused to consider it.' Somerville's and Mehaffey's positions were to be crucial in the decisions on the Major Hall that would be taken post-Utzon.