Complex sentence: A peer-reviewed study in 2006 seemed to confirm the second of these options, by testing the different effect of HFCs when presented via loudspeakers or via headphones-the hypersonic effect did not occur when the HFCs were presented via earphones.
Split into simpler sentences: A peer-reviewed study in 2006 seemed to confirm the second of these options, by testing the different effect of HFCs when presented via loudspeakers or via headphones. The hypersonic effect did not occur when the HFCs were presented via earphones.