‍

Why this study now? 

Audio use has exploded across devices—smart speakers, phones, and apps—making commercial audio truly multi-platform. While broadcast radio still delivers the largest share of listening, IP-delivered audio (radio streams, podcasts, music services) now accounts for nearly half of commercial audio time. Despite that audience growth and richer cross-platform buying options, multi-platform audio ad spend is lagging. Interviews with advertisers surfaced the blocker: they want hard, comparable ROI evidence—especially to justify digital audio’s price premium.

Data & method

Rather than start from scratch, the team mined the award-winning Profit Ability 2 database (UK, but with transferable learnings): 141 brands, £1.8bn in media, 14 sectors, 10 channels, all modeled via MMM to isolate incremental profit (both short-term, up to 13 weeks, and long-term, up to 2 years). For this audio-focused cut, analysts identified seven brands with sufficient spend split to model broadcast radio (linear, non-IP) separately from digital audio (IP radio, podcasts, music streaming). Results were indexed to compare across brands and against the all-media average.

Headline ROI results

• Audio overall outperforms the market:
  • Full-term profit ROI (short + long): £5.00 per £1 spent vs all-media average £4.11 (+21%).
  • Short-term profit ROI: £2.50 vs £1.87 (+32%)
• Both components are strong—digital and broadcast:
  • Full-term ROI: Digital audio £5.20, Broadcast £4.80 (both > average).
  • Short-term ROI: Digital £2.70, Broadcast £2.30 (both > average).
  Digital’s edge partly reflects diminishing returns (it tends to be a smaller, less saturated line in the mix), but the key point is that both forms clear the ROI bar—even with digital’s higher CPMs.

What adding audio does to total campaigns

Comparing otherwise similar plans without audio (indexed to 100) vs plans with audio (avg 15% of spend, incl. ~5% digital audio) showed a +5% lift in short-term campaign ROI. Next, the team modeled headroom using marginal ROI curves to find the point where the last £ spent still returns at least £1 profit. Blending math with practical buying constraints, they recommend lifting audio to ~24% of total media (~16% broadcast, ~8% digital). In the dataset, that reallocation delivered an ~8.2% short-term ROI gain vs plans with no audio at all.

Practical implications

1. Be more ambitious with audio.
   The evidence supports pushing audio to ~20% of media budget as a rule of thumb (context-dependent). This aligns with prior Radiocentre ROI work and time-use data (audio ≈ a quarter of media time), giving confidence from multiple sources.
2. Reallocate from “pure-play” internet budgets first.
   Given sheer budget weight and attention concerns, that’s where flexibility exists. On short-term profit ROI, audio beats most pure-play digital channels (only generic PPC comes close). On full-term ROI, both broadcast and digital audio exceed individual pure-play internet channels by 30%+, strengthening the case to rebalance.
3. Supplement, don’t substitute.
   Use broadcast radio + digital audio together. Broadcast builds broad reach and future demand; digital audio adds addressability, recency, and extra weekly reach—maximizing effective frequency and conversion of existing demand. The duo is complementary, not either/or.
4. Instrument your models.
   Separate broadcast and digital audio lines in MMM/MTA so you (and the industry) get clearer diagnostics on each component. The study had to hunt for brands with that split—doing this routinely will improve future optimization.

Conclusion

Advertisers are under-invested in multi-platform audio relative to its proven profit returns. Both broadcast radio and digital audio outperform the all-media average in the short and the long term; used together—and funded to their marginal ROI headroom—they can lift total campaign ROI meaningfully (≈ +8% in the study’s scenario) while justifying digital’s premium and preserving the scale and efficiency of broadcast.

‍

You can view a recording of the presentation and download the presentation deck by clicking the buttons below.