The new six week old macroprudential measures of APRA, centred on interest-only loans, are about "breathing space [that] lessens the financial amplification of the cycle," Philip Lowe, governor of the Reserve Bank of Australia, told a Queensland economists' lunch yesterday."APRA's measures are not targeted at high housing prices," Lowe insisted, after a long preamble on stalwart RBA themes of supply and demand in national and regional property markets.The international evidence was "that these types of measures cannot sustainably address pressures on housing prices originating from the underlying supply-demand balance," Lowe said."But they can provide some breathing space while the underlying issues are addressed. In doing so, they can help lessen the financial amplification of the cycle that I spoke about before. "Reducing this amplification while a better balance is established between supply and demand in the housing market can help with the resilience of our economy."It was Lowe's second speech since APRA rolled out a public relations campaign, at the end of March, to rub the shine off credit growth. The RBA governor, keen to be involved, confronted topics widely aired in the public domain but obscured by his agency and other financial regulators."At some point," he conceded, "interest rates in Australia will increase. To be clear, this is not a signal about the near-term outlook for interest rates in Australia but rather a reminder that over time we could expect interest rates to rise, not least because of global developments.... We should not, though, expect interest rates always to be this low."Lowe used the speech to frame the reduction in consumer spending feared, in the context of any broader hike in interest rates, for "resilience."Lowe said that "with interest rates as low as they have been, and prices rising, many people have found it attractive to borrow money to invest in an asset whose price is increasing. The result has been strong growth in borrowing by investors, with investors accounting for 30 to 40 per cent of new loans."This borrowing is not the underlying cause of the higher housing prices. "It has acted as a financial amplifier in some cities, adding to the already upward pressure on prices. "In terms of resilience, my overall assessment is that the recent increase in household debt relative to our incomes has made the economy less resilient to future shocks. "Given this assessment, the Reserve Bank has strongly supported the prudential measures undertaken by APRA. Double-digit growth in debt owed by investors at a time of weak income growth cannot be strengthening the resilience of our economy. Nor can a high concentration of interest-only loans."One of his conclusions:"I want to make it clear that the Reserve Bank does not have a target for the debt-to-income ratio or the ratio of nationwide housing prices to income."