Drivers and team members are at odds over whether this year's Formula 1 engines are louder following the first F1 test in Jerez, a year after the 'new sound' from the latest generation engines drew the ire of many .

F1 roared back into action for 2015 with a four-day test in Spain last week, with one particular development emerging after several bystanders noted an apparent increase in the volume and tone of the engines compared with their 2014 variants.

However, when drivers and teams were quizzed over whether there had been fundamental changes to the engines to improve the sound output, opinions were decidedly mixed.

"The noise in the car is very different compared to on the audio out of it," said Romain Grosjean, whose Lotus team has switched from Renault to Mercedes power units for 2015. "It isn't as clear as in the V8s on the downshift. But overall it does sound louder than last year which is quite nice."

"For me it's exactly the same," reigning champion Lewis Hamilton countered. "I've only heard it from in the garage. I was reminiscing about the old V10s and V8s when we used to start them up. It doesn't sound as special as those. But at the end I was braking and accelerating, and the power - that's quite special."

Mercedes' Paddy Lowe was also sceptical about the suggestions, claiming the Jerez circuit - with its high spectator banks - amplifies the sound. He also suggests the engines may seem louder simply because 'our ears reset over Christmas'.

"[It is] much debated on the pit wall and in the factories," he admitted. "We've done checks but I don't have any accurate measurements to tell us whether we are louder today than this time 365 days ago. Our development work is aimed at going faster and more efficient. Is it louder? I can't answer that and I certainly can't quantify it.

"Maybe it's because we've been away from racing cars for the past two or three months and it is just nice to hear the sound again and maybe because the track is a bit of an amphitheatre with the sound is bouncing off the hills compared with wide open Abu Dhabi where we last time. We might have had a bit of motorsport reset in our ears over Christmas."

Though it is a debate that has consumed F1 since the start of 2014 when the new generation engines were introduced, Williams' chief technical officer Pat Symonds says he is disappointed that a 'trivial' subject is still being discussed given the 'stunning improvements' made by the sport.

"In the overall scheme of things and the spectacle of Formula 1, and with the absolutely stunning improvements we have made in the efficiency of the cars, bringing them into the 21st century and making them relevant to society and trying to provide some engineering expertise that does actually have some benefit to the general public, I find it a great shame that people are talking about the noise. It is such a trivial subject, it really is."