The Tottenham Hotspur Supporters' Trust says "unaffordable" ticket prices are behind the declining atmosphere at the club's stadium.
Spurs have struggled for results in their 62,850-seater ground this year, winning three of 20 home Premier League games in 2025.
And, while the venue came alive during last season's successful Europa League campaign, the club's return to the Champions League this term has resulted in lowly crowds of 54,755 and 49,565 for home fixtures against Villarreal and Copenhagen.
Boos have also been a frequent feature, despite new boss Thomas Frank talking up the need to turn the stadium into a fortress.
The Supporters' Trust says fans are being priced out of attending games and have urged the club to extend its young adult category to ages 18-25 and make young adult concessions available for all matches.
"Over the last couple of seasons, it's undeniable that the atmosphere has declined at Tottenham Hotspur Stadium. The reasons are simple -- too many empty seats and too many supporters, particularly young supporters, priced out of attending. Thin the crowd and you thin the noise," a THST statement read.
"Europa League nights last season, with sensibly-priced tickets, proved the point: fair ticket pricing fills the ground, often with the next generation of Spurs fans. And the noise follows.
"This season, the illusion has gone. The Champions League -- our flagship nights -- has seen thousands of empty seats, in our view due to unrealistic and unaffordable match pricing.
"Even big Premier League games have shown gaps we've never known at Tottenham. A world-class stadium without a full house is only half a home.
"The South Stand -- 17,000 strong -- was a brilliant idea, but it hasn't consistently fulfilled its potential. It's not yet the relentless wall of sound we all dreamt of and that's a problem pricing and access can fix.
"We're asking the club to make ticketing fair and affordable and encourage the next generation of all match-going fans, so the stands are packed, every match, all season. Fill our home -- and we'll find our voice again."
The PA news agency has contacted Tottenham for comment, but the club recently announced the visit of Borussia Dortmund in January will now have Category B pricing instead of Category A and ticket prices set for this season were made in the summer when Daniel Levy was still chairman.
Radu Dragusin, meanwhile, has been stepping up his recovery from an ACL injury suffered in January.
The Romania centre-back, who recently returned to training, played 45 minutes in a behind-closed-doors friendly against Leyton Orient on Wednesday.
Dragusin could be involved again for the first team after the international break, with Spurs set to face north London rivals Arsenal on Nov. 23.